Commit Graph

116 Commits

Author SHA1 Message Date
Mike Rapoport
78179556e7 mm/gup.c: fix follow_page_mask() kerneldoc comment
Commit df06b37ffe ("mm/gup: cache dev_pagemap while pinning pages")
modified the signature of follow_page_mask() but left the parameter
description behind.

Update the description to make the code and comments agree again.

While at it, update formatting of the return value description to match
Documentation/doc-guide/kernel-doc.rst guidelines.

Link: http://lkml.kernel.org/r/1541603316-27832-1-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-11-18 10:15:10 -08:00
Fengguang Wu
2ebe82288b mm/gup.c: fix __get_user_pages_fast() comment
mmu_gather_tlb() no longer exists.  Replace with mmu_table_batch().

Link: http://lkml.kernel.org/r/20180928053441.rpzwafzlsnp74mkl@wfg-t540p.sh.intel.com
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Kosina <trivial@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-31 08:54:17 -07:00
Keith Busch
df06b37ffe mm/gup: cache dev_pagemap while pinning pages
Getting pages from ZONE_DEVICE memory needs to check the backing device's
live-ness, which is tracked in the device's dev_pagemap metadata.  This
metadata is stored in a radix tree and looking it up adds measurable
software overhead.

This patch avoids repeating this relatively costly operation when
dev_pagemap is used by caching the last dev_pagemap while getting user
pages.  The gup_benchmark kernel self test reports this reduces time to
get user pages to as low as 1/3 of the previous time.

Link: http://lkml.kernel.org/r/20181012173040.15669-1-keith.busch@intel.com
Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 16:38:15 -07:00
Wei Yang
d4faa40259 mm: remove unnecessary local variable addr in __get_user_pages_fast()
The local variable `addr' in __get_user_pages_fast() is just a shadow of
`start'.  Since `start' never changes after assignment to `addr', it is
fine to replace `start' with it.

Also the meaning of [start, end] is more obvious than [addr, end] when
passed to gup_pgd_range().

Link: http://lkml.kernel.org/r/20180925021448.20265-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 16:26:34 -07:00
Souptick Joarder
2b74030354 mm: Change return type int to vm_fault_t for fault handlers
Use new return type vm_fault_t for fault handler.  For now, this is just
documenting that the function returns a VM_FAULT value rather than an
errno.  Once all instances are converted, vm_fault_t will become a
distinct type.

Ref-> commit 1c8f422059 ("mm: change return type to vm_fault_t")

The aim is to change the return type of finish_fault() and
handle_mm_fault() to vm_fault_t type.  As part of that clean up return
type of all other recursively called functions have been changed to
vm_fault_t type.

The places from where handle_mm_fault() is getting invoked will be
change to vm_fault_t type but in a separate patch.

vmf_error() is the newly introduce inline function in 4.17-rc6.

[akpm@linux-foundation.org: don't shadow outer local `ret' in __do_huge_pmd_anonymous_page()]
Link: http://lkml.kernel.org/r/20180604171727.GA20279@jordon-HP-15-Notebook-PC
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-23 18:48:44 -07:00
Michal Hocko
bb177a732c mm: do not bug_on on incorrect length in __mm_populate()
syzbot has noticed that a specially crafted library can easily hit
VM_BUG_ON in __mm_populate

  kernel BUG at mm/gup.c:1242!
  invalid opcode: 0000 [] SMP
  CPU: 2 PID: 9667 Comm: a.out Not tainted 4.18.0-rc3 
  Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017
  RIP: 0010:__mm_populate+0x1e2/0x1f0
  Code: 55 d0 65 48 33 14 25 28 00 00 00 89 d8 75 21 48 83 c4 20 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 75 18 f1 ff 0f 0b e8 6e 18 f1 ff <0f> 0b 31 db eb c9 e8 93 06 e0 ff 0f 1f 00 55 48 89 e5 53 48 89 fb
  Call Trace:
     vm_brk_flags+0xc3/0x100
     vm_brk+0x1f/0x30
     load_elf_library+0x281/0x2e0
     __ia32_sys_uselib+0x170/0x1e0
     do_fast_syscall_32+0xca/0x420
     entry_SYSENTER_compat+0x70/0x7f

The reason is that the length of the new brk is not page aligned when we
try to populate the it.  There is no reason to bug on that though.
do_brk_flags already aligns the length properly so the mapping is
expanded as it should.  All we need is to tell mm_populate about it.
Besides that there is absolutely no reason to to bug_on in the first
place.  The worst thing that could happen is that the last page wouldn't
get populated and that is far from putting system into an inconsistent
state.

Fix the issue by moving the length sanitization code from do_brk_flags
up to vm_brk_flags.  The only other caller of do_brk_flags is brk
syscall entry and it makes sure to provide the proper length so t here
is no need for sanitation and so we can use do_brk_flags without it.

Also remove the bogus BUG_ONs.

[osalvador@techadventures.net: fix up vm_brk_flags s@request@len@]
Link: http://lkml.kernel.org/r/20180706090217.GI32658@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: syzbot <syzbot+5dcb560fe12aa5091c06@syzkaller.appspotmail.com>
Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-07-14 11:11:10 -07:00
Linus Torvalds
7d3bf613e9 libnvdimm for 4.18
* DAX broke a fundamental assumption of truncate of file mapped pages.
   The truncate path assumed that it is safe to disconnect a pinned page
   from a file and let the filesystem reclaim the physical block. With DAX
   the page is equivalent to the filesystem block. Introduce
   dax_layout_busy_page() to enable filesystems to wait for pinned DAX
   pages to be released. Without this wait a filesystem could allocate
   blocks under active device-DMA to a new file.
 
 * DAX arranges for the block layer to be bypassed and uses
   dax_direct_access() + copy_to_iter() to satisfy read(2) calls.
   However, the memcpy_mcsafe() facility is available through the pmem
   block driver. In order to safely handle media errors, via the DAX
   block-layer bypass, introduce copy_to_iter_mcsafe().
 
 * Fix cache management policy relative to the ACPI NFIT Platform
   Capabilities Structure to properly elide cache flushes when they are not
   necessary. The table indicates whether CPU caches are power-fail
   protected. Clarify that a deep flush is always performed on
   REQ_{FUA,PREFLUSH} requests.
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Merge tag 'libnvdimm-for-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull libnvdimm updates from Dan Williams:
 "This adds a user for the new 'bytes-remaining' updates to
  memcpy_mcsafe() that you already received through Ingo via the
  x86-dax- for-linus pull.

  Not included here, but still targeting this cycle, is support for
  handling memory media errors (poison) consumed via userspace dax
  mappings.

  Summary:

   - DAX broke a fundamental assumption of truncate of file mapped
     pages. The truncate path assumed that it is safe to disconnect a
     pinned page from a file and let the filesystem reclaim the physical
     block. With DAX the page is equivalent to the filesystem block.
     Introduce dax_layout_busy_page() to enable filesystems to wait for
     pinned DAX pages to be released. Without this wait a filesystem
     could allocate blocks under active device-DMA to a new file.

   - DAX arranges for the block layer to be bypassed and uses
     dax_direct_access() + copy_to_iter() to satisfy read(2) calls.
     However, the memcpy_mcsafe() facility is available through the pmem
     block driver. In order to safely handle media errors, via the DAX
     block-layer bypass, introduce copy_to_iter_mcsafe().

   - Fix cache management policy relative to the ACPI NFIT Platform
     Capabilities Structure to properly elide cache flushes when they
     are not necessary. The table indicates whether CPU caches are
     power-fail protected. Clarify that a deep flush is always performed
     on REQ_{FUA,PREFLUSH} requests"

* tag 'libnvdimm-for-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (21 commits)
  dax: Use dax_write_cache* helpers
  libnvdimm, pmem: Do not flush power-fail protected CPU caches
  libnvdimm, pmem: Unconditionally deep flush on *sync
  libnvdimm, pmem: Complete REQ_FLUSH => REQ_PREFLUSH
  acpi, nfit: Remove ecc_unit_size
  dax: dax_insert_mapping_entry always succeeds
  libnvdimm, e820: Register all pmem resources
  libnvdimm: Debug probe times
  linvdimm, pmem: Preserve read-only setting for pmem devices
  x86, nfit_test: Add unit test for memcpy_mcsafe()
  pmem: Switch to copy_to_iter_mcsafe()
  dax: Report bytes remaining in dax_iomap_actor()
  dax: Introduce a ->copy_to_iter dax operation
  uio, lib: Fix CONFIG_ARCH_HAS_UACCESS_MCSAFE compilation
  xfs, dax: introduce xfs_break_dax_layouts()
  xfs: prepare xfs_break_layouts() for another layout type
  xfs: prepare xfs_break_layouts() to be called with XFS_MMAPLOCK_EXCL
  mm, fs, dax: handle layout changes to pinned dax mappings
  mm: fix __gup_device_huge vs unmap
  mm: introduce MEMORY_DEVICE_FS_DAX and CONFIG_DEV_PAGEMAP_OPS
  ...
2018-06-08 17:21:52 -07:00
Dan Williams
b56845794e Merge branch 'for-4.18/dax' into libnvdimm-for-next 2018-06-08 15:16:40 -07:00
Huang Ying
688272809f mm, gup: prevent pmd checking race in follow_pmd_mask()
mmap_sem will be read locked when calling follow_pmd_mask().  But this
cannot prevent PMD from being changed for all cases when PTL is
unlocked, for example, from pmd_trans_huge() to pmd_none() via
MADV_DONTNEED.  So it is possible for the pmd_present() check in
follow_pmd_mask() to encounter an invalid PMD.  This may cause an
incorrect VM_BUG_ON() or an infinite loop.  Fix this by reading the PMD
entry into a local variable with READ_ONCE() and checking the local
variable and pmd_none() in the retry loop.

As Kirill pointed out, with PTL unlocked, the *pmd may be changed under
us, so reading it directly again and again may incur weird bugs.  So
although using *pmd directly other than for pmd_present() checking may
be safe, it is still better to replace them to read *pmd once and check
the local variable multiple times.

When PTL unlocked, replace all *pmd with local variable was suggested by
Kirill.

Link: http://lkml.kernel.org/r/20180419083514.1365-1-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-07 17:34:35 -07:00
Laurent Dufour
3010a5ea66 mm: introduce ARCH_HAS_PTE_SPECIAL
Currently the PTE special supports is turned on in per architecture
header files.  Most of the time, it is defined in
arch/*/include/asm/pgtable.h depending or not on some other per
architecture static definition.

This patch introduce a new configuration variable to manage this
directly in the Kconfig files.  It would later replace
__HAVE_ARCH_PTE_SPECIAL.

Here notes for some architecture where the definition of
__HAVE_ARCH_PTE_SPECIAL is not obvious:

arm
 __HAVE_ARCH_PTE_SPECIAL which is currently defined in
arch/arm/include/asm/pgtable-3level.h which is included by
arch/arm/include/asm/pgtable.h when CONFIG_ARM_LPAE is set.
So select ARCH_HAS_PTE_SPECIAL if ARM_LPAE.

powerpc
__HAVE_ARCH_PTE_SPECIAL is defined in 2 files:
 - arch/powerpc/include/asm/book3s/64/pgtable.h
 - arch/powerpc/include/asm/pte-common.h
The first one is included if (PPC_BOOK3S & PPC64) while the second is
included in all the other cases.
So select ARCH_HAS_PTE_SPECIAL all the time.

sparc:
__HAVE_ARCH_PTE_SPECIAL is defined if defined(__sparc__) &&
defined(__arch64__) which are defined through the compiler in
sparc/Makefile if !SPARC32 which I assume to be if SPARC64.
So select ARCH_HAS_PTE_SPECIAL if SPARC64

There is no functional change introduced by this patch.

Link: http://lkml.kernel.org/r/1523433816-14460-2-git-send-email-ldufour@linux.vnet.ibm.com
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Suggested-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Albert Ou <albert@sifive.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Christophe LEROY <christophe.leroy@c-s.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-07 17:34:35 -07:00
Dan Williams
a9b6de77b1 mm: fix __gup_device_huge vs unmap
get_user_pages_fast() for device pages is missing the typical validation
that all page references have been taken while the mapping was valid.
Without this validation truncate operations can not reliably coordinate
against new page reference events like O_DIRECT.

Cc: <stable@vger.kernel.org>
Fixes: 3565fce3a6 ("mm, x86: get_user_pages() for dax mappings")
Reported-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-05-22 07:19:08 -07:00
Willy Tarreau
7f7ccc2ccc proc: do not access cmdline nor environ from file-backed areas
proc_pid_cmdline_read() and environ_read() directly access the target
process' VM to retrieve the command line and environment. If this
process remaps these areas onto a file via mmap(), the requesting
process may experience various issues such as extra delays if the
underlying device is slow to respond.

Let's simply refuse to access file-backed areas in these functions.
For this we add a new FOLL_ANON gup flag that is passed to all calls
to access_remote_vm(). The code already takes care of such failures
(including unmapped areas). Accesses via /proc/pid/mem were not
changed though.

This was assigned CVE-2018-1120.

Note for stable backports: the patch may apply to kernels prior to 4.11
but silently miss one location; it must be checked that no call to
access_remote_vm() keeps zero as the last argument.

Reported-by: Qualys Security Advisory <qsa@qualys.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-05-17 09:27:47 -07:00
Michael S. Tsirkin
d081107867 mm/gup.c: document return value
__get_user_pages_fast handles errors differently from
get_user_pages_fast: the former always returns the number of pages
pinned, the later might return a negative error code.

Link: http://lkml.kernel.org/r/1522962072-182137-6-git-send-email-mst@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-13 17:10:27 -07:00
Michael S. Tsirkin
c61611f709 get_user_pages_fast(): return -EFAULT on access_ok failure
get_user_pages_fast is supposed to be a faster drop-in equivalent of
get_user_pages.  As such, callers expect it to return a negative return
code when passed an invalid address, and never expect it to return 0
when passed a positive number of pages, since its documentation says:

 * Returns number of pages pinned. This may be fewer than the number
 * requested. If nr_pages is 0 or negative, returns 0. If no pages
 * were pinned, returns -errno.

When get_user_pages_fast fall back on get_user_pages this is exactly
what happens.  Unfortunately the implementation is inconsistent: it
returns 0 if passed a kernel address, confusing callers: for example,
the following is pretty common but does not appear to do the right thing
with a kernel address:

        ret = get_user_pages_fast(addr, 1, writeable, &page);
        if (ret < 0)
                return ret;

Change get_user_pages_fast to return -EFAULT when supplied a kernel
address to make it match expectations.

All callers have been audited for consistency with the documented
semantics.

Link: http://lkml.kernel.org/r/1522962072-182137-4-git-send-email-mst@redhat.com
Fixes: 5b65c4677a ("mm, x86/mm: Fix performance regression in get_user_pages_fast()")
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reported-by: syzbot+6304bf97ef436580fede@syzkaller.appspotmail.com
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-13 17:10:27 -07:00
Mario Leinweber
2923117b71 mm/gup.c: fix coding style issues.
- Fixed style error: 8 spaces -> 1 tab.
- Fixed style warning: Corrected misleading indentation.

Link: http://lkml.kernel.org/r/20180302210254.31888-1-marioleinweber@web.de
Signed-off-by: Mario Leinweber <marioleinweber@web.de>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-05 21:36:26 -07:00
Andrea Arcangeli
96312e6128 mm/gup.c: teach get_user_pages_unlocked to handle FOLL_NOWAIT
KVM is hanging during postcopy live migration with userfaultfd because
get_user_pages_unlocked is not capable to handle FOLL_NOWAIT.

Earlier FOLL_NOWAIT was only ever passed to get_user_pages.

Specifically faultin_page (the callee of get_user_pages_unlocked caller)
doesn't know that if FAULT_FLAG_RETRY_NOWAIT was set in the page fault
flags, when VM_FAULT_RETRY is returned, the mmap_sem wasn't actually
released (even if nonblocking is not NULL).  So it sets *nonblocking to
zero and the caller won't release the mmap_sem thinking it was already
released, but it wasn't because of FOLL_NOWAIT.

Link: http://lkml.kernel.org/r/20180302174343.5421-2-aarcange@redhat.com
Fixes: ce53053ce3 ("kvm: switch get_user_page_nowait() to get_user_pages_unlocked()")
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Tested-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-03-09 16:40:01 -08:00
Linus Torvalds
3ff1b28caa libnvdimm for 4.16
* Require struct page by default for filesystem DAX to remove a number of
   surprising failure cases.  This includes failures with direct I/O, gdb and
   fork(2).
 
 * Add support for the new Platform Capabilities Structure added to the NFIT in
   ACPI 6.2a.  This new table tells us whether the platform supports flushing
   of CPU and memory controller caches on unexpected power loss events.
 
 * Revamp vmem_altmap and dev_pagemap handling to clean up code and better
   support future future PCI P2P uses.
 
 * Deprecate the ND_IOCTL_SMART_THRESHOLD command whose payload has become
   out-of-sync with recent versions of the NVDIMM_FAMILY_INTEL spec, and
   instead rely on the generic ND_CMD_CALL approach used by the two other IOCTL
   families, NVDIMM_FAMILY_{HPE,MSFT}.
 
 * Enhance nfit_test so we can test some of the new things added in version 1.6
   of the DSM specification.  This includes testing firmware download and
   simulating the Last Shutdown State (LSS) status.
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Merge tag 'libnvdimm-for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull libnvdimm updates from Ross Zwisler:

 - Require struct page by default for filesystem DAX to remove a number
   of surprising failure cases. This includes failures with direct I/O,
   gdb and fork(2).

 - Add support for the new Platform Capabilities Structure added to the
   NFIT in ACPI 6.2a. This new table tells us whether the platform
   supports flushing of CPU and memory controller caches on unexpected
   power loss events.

 - Revamp vmem_altmap and dev_pagemap handling to clean up code and
   better support future future PCI P2P uses.

 - Deprecate the ND_IOCTL_SMART_THRESHOLD command whose payload has
   become out-of-sync with recent versions of the NVDIMM_FAMILY_INTEL
   spec, and instead rely on the generic ND_CMD_CALL approach used by
   the two other IOCTL families, NVDIMM_FAMILY_{HPE,MSFT}.

 - Enhance nfit_test so we can test some of the new things added in
   version 1.6 of the DSM specification. This includes testing firmware
   download and simulating the Last Shutdown State (LSS) status.

* tag 'libnvdimm-for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (37 commits)
  libnvdimm, namespace: remove redundant initialization of 'nd_mapping'
  acpi, nfit: fix register dimm error handling
  libnvdimm, namespace: make min namespace size 4K
  tools/testing/nvdimm: force nfit_test to depend on instrumented modules
  libnvdimm/nfit_test: adding support for unit testing enable LSS status
  libnvdimm/nfit_test: add firmware download emulation
  nfit-test: Add platform cap support from ACPI 6.2a to test
  libnvdimm: expose platform persistence attribute for nd_region
  acpi: nfit: add persistent memory control flag for nd_region
  acpi: nfit: Add support for detect platform CPU cache flush on power loss
  device-dax: Fix trailing semicolon
  libnvdimm, btt: fix uninitialized err_lock
  dax: require 'struct page' by default for filesystem dax
  ext2: auto disable dax instead of failing mount
  ext4: auto disable dax instead of failing mount
  mm, dax: introduce pfn_t_special()
  mm: Fix devm_memremap_pages() collision handling
  mm: Fix memory size alignment in devm_memremap_pages_release()
  memremap: merge find_dev_pagemap into get_dev_pagemap
  memremap: change devm_memremap_pages interface to use struct dev_pagemap
  ...
2018-02-06 10:41:33 -08:00
Linus Torvalds
5a87e37ee0 Merge branch 'work.get_user_pages_fast' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull get_user_pages_fast updates from Al Viro:
 "A bit more get_user_pages work"

* 'work.get_user_pages_fast' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  kvm: switch get_user_page_nowait() to get_user_pages_unlocked()
  __get_user_pages_locked(): get rid of notify_drop argument
  get_user_pages_unlocked(): pass true to __get_user_pages_locked() notify_drop
  cris: switch to get_user_pages_fast()
  fold __get_user_pages_unlocked() into its sole remaining caller
2018-01-31 10:01:08 -08:00
Christoph Hellwig
832d7aa051 mm: optimize dev_pagemap reference counting around get_dev_pagemap
Change the calling convention so that get_dev_pagemap always consumes the
previous reference instead of doing this using an explicit earlier call to
put_dev_pagemap in the callers.

The callers will still need to put the final reference after finishing the
loop over the pages.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-01-08 11:46:23 -08:00
Linus Torvalds
f6f3732162 Revert "mm: replace p??_write with pte_access_permitted in fault + gup paths"
This reverts commits 5c9d2d5c26, c7da82b894, and e7fe7b5cae.

We'll probably need to revisit this, but basically we should not
complicate the get_user_pages_fast() case, and checking the actual page
table protection key bits will require more care anyway, since the
protection keys depend on the exact state of the VM in question.

Particularly when doing a "remote" page lookup (ie in somebody elses VM,
not your own), you need to be much more careful than this was.  Dave
Hansen says:

 "So, the underlying bug here is that we now a get_user_pages_remote()
  and then go ahead and do the p*_access_permitted() checks against the
  current PKRU. This was introduced recently with the addition of the
  new p??_access_permitted() calls.

  We have checks in the VMA path for the "remote" gups and we avoid
  consulting PKRU for them. This got missed in the pkeys selftests
  because I did a ptrace read, but not a *write*. I also didn't
  explicitly test it against something where a COW needed to be done"

It's also not entirely clear that it makes sense to check the protection
key bits at this level at all.  But one possible eventual solution is to
make the get_user_pages_fast() case just abort if it sees protection key
bits set, which makes us fall back to the regular get_user_pages() case,
which then has a vma and can do the check there if we want to.

We'll see.

Somewhat related to this all: what we _do_ want to do some day is to
check the PAGE_USER bit - it should obviously always be set for user
pages, but it would be a good check to have back.  Because we have no
generic way to test for it, we lost it as part of moving over from the
architecture-specific x86 GUP implementation to the generic one in
commit e585513b76 ("x86/mm/gup: Switch GUP to the generic
get_user_page_fast() implementation").

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-12-15 18:53:22 -08:00
Al Viro
e716712f83 __get_user_pages_locked(): get rid of notify_drop argument
The only caller that doesn't pass true in it is get_user_pages() and
it passes NULL in locked.  The only place where we check it is
	if (notify_locked && lock_dropped && *locked)
and lock_dropped can become true only if we have locked != NULL.
In other words, the second part of condition will be false when
called by get_user_pages().

Just get rid of the argument and turn the condition into
	if (lock_dropped && *locked)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-12-02 20:29:13 -05:00
Al Viro
14cb138d7c get_user_pages_unlocked(): pass true to __get_user_pages_locked() notify_drop
Equivalent transformation - the only place in __get_user_pages_locked()
where we look at notify_drop argument is
	if (notify_drop && lock_dropped && *locked) {
		up_read(&mm->mmap_sem);
		*locked = 0;
	}
in the very end.  Changing notify_drop from false to true won't change
behaviour unless *locked is non-zero.  The caller is
        ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
			      &locked, false, gup_flags | FOLL_TOUCH);
	if (locked)
		up_read(&mm->mmap_sem);
so in that case the original kernel would have done up_read() right after
return from __get_user_pages_locked(), while the modified one would've done
it right before the return.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-12-02 20:29:12 -05:00
Al Viro
c803c9c6c9 fold __get_user_pages_unlocked() into its sole remaining caller
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-12-02 20:29:11 -05:00
Dan Williams
2bb6d28370 mm: introduce get_user_pages_longterm
Patch series "introduce get_user_pages_longterm()", v2.

Here is a new get_user_pages api for cases where a driver intends to
keep an elevated page count indefinitely.  This is distinct from usages
like iov_iter_get_pages where the elevated page counts are transient.
The iov_iter_get_pages cases immediately turn around and submit the
pages to a device driver which will put_page when the i/o operation
completes (under kernel control).

In the longterm case userspace is responsible for dropping the page
reference at some undefined point in the future.  This is untenable for
filesystem-dax case where the filesystem is in control of the lifetime
of the block / page and needs reasonable limits on how long it can wait
for pages in a mapping to become idle.

Fixing filesystems to actually wait for dax pages to be idle before
blocks from a truncate/hole-punch operation are repurposed is saved for
a later patch series.

Also, allowing longterm registration of dax mappings is a future patch
series that introduces a "map with lease" semantic where the kernel can
revoke a lease and force userspace to drop its page references.

I have also tagged these for -stable to purposely break cases that might
assume that longterm memory registrations for filesystem-dax mappings
were supported by the kernel.  The behavior regression this policy
change implies is one of the reasons we maintain the "dax enabled.
Warning: EXPERIMENTAL, use at your own risk" notification when mounting
a filesystem in dax mode.

It is worth noting the device-dax interface does not suffer the same
constraints since it does not support file space management operations
like hole-punch.

This patch (of 4):

Until there is a solution to the dma-to-dax vs truncate problem it is
not safe to allow long standing memory registrations against
filesytem-dax vmas.  Device-dax vmas do not have this problem and are
explicitly allowed.

This is temporary until a "memory registration with layout-lease"
mechanism can be implemented for the affected sub-systems (RDMA and
V4L2).

[akpm@linux-foundation.org: use kcalloc()]
Link: http://lkml.kernel.org/r/151068939435.7446.13560129395419350737.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: 3565fce3a6 ("mm, x86: get_user_pages() for dax mappings")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Hal Rosenstock <hal.rosenstock@gmail.com>
Cc: Inki Dae <inki.dae@samsung.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Joonyoung Shim <jy0922.shim@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Seung-Woo Kim <sw0312.kim@samsung.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-29 18:40:42 -08:00
Dan Williams
5c9d2d5c26 mm: replace pte_write with pte_access_permitted in fault + gup paths
The 'access_permitted' helper is used in the gup-fast path and goes
beyond the simple _PAGE_RW check to also:

 - validate that the mapping is writable from a protection keys
   standpoint

 - validate that the pte has _PAGE_USER set since all fault paths where
   pte_write is must be referencing user-memory.

Link: http://lkml.kernel.org/r/151043111604.2842.8051684481794973100.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-29 18:40:42 -08:00
Ingo Molnar
967535223f Merge branch 'x86/urgent' into x86/mm, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-20 13:06:52 +02:00
Kirill A. Shutemov
5b65c4677a mm, x86/mm: Fix performance regression in get_user_pages_fast()
The 0-day test bot found a performance regression that was tracked down to
switching x86 to the generic get_user_pages_fast() implementation:

  http://lkml.kernel.org/r/20170710024020.GA26389@yexl-desktop

The regression was caused by the fact that we now use local_irq_save() +
local_irq_restore() in get_user_pages_fast() to disable interrupts.
In x86 implementation local_irq_disable() + local_irq_enable() was used.

The fix is to make get_user_pages_fast() use local_irq_disable(),
leaving local_irq_save() for __get_user_pages_fast() that can be called
with interrupts disabled.

Numbers for pinning a gigabyte of memory, one page a time, 20 repeats:

  Before:  Average: 14.91 ms, stddev: 0.45 ms
  After:   Average: 10.76 ms, stddev: 0.18 ms

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>
Cc: linux-mm@kvack.org
Fixes: e585513b76 ("x86/mm/gup: Switch GUP to the generic get_user_page_fast() implementation")
Link: http://lkml.kernel.org/r/20170908215603.9189-3-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-13 11:26:52 +02:00
Jérôme Glisse
df6ad69838 mm/device-public-memory: device memory cache coherent with CPU
Platform with advance system bus (like CAPI or CCIX) allow device memory
to be accessible from CPU in a cache coherent fashion.  Add a new type of
ZONE_DEVICE to represent such memory.  The use case are the same as for
the un-addressable device memory but without all the corners cases.

Link: http://lkml.kernel.org/r/20170817000548.32038-19-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 18:26:46 -07:00
Zi Yan
84c3fc4e9c mm: thp: check pmd migration entry in common path
When THP migration is being used, memory management code needs to handle
pmd migration entries properly.  This patch uses !pmd_present() or
is_swap_pmd() (depending on whether pmd_none() needs separate code or
not) to check pmd migration entries at the places where a pmd entry is
present.

Since pmd-related code uses split_huge_page(), split_huge_pmd(),
pmd_trans_huge(), pmd_trans_unstable(), or
pmd_none_or_trans_huge_or_clear_bad(), this patch:

1. adds pmd migration entry split code in split_huge_pmd(),

2. takes care of pmd migration entries whenever pmd_trans_huge() is present,

3. makes pmd_none_or_trans_huge_or_clear_bad() pmd migration entry aware.

Since split_huge_page() uses split_huge_pmd() and pmd_trans_unstable()
is equivalent to pmd_none_or_trans_huge_or_clear_bad(), we do not change
them.

Until this commit, a pmd entry should be:
1. pointing to a pte page,
2. is_swap_pmd(),
3. pmd_trans_huge(),
4. pmd_devmap(), or
5. pmd_none().

Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 18:26:45 -07:00
Oliver O'Halloran
09180ca4b3 mm/gup: make __gup_device_* require THP
These functions are the only bits of generic code that use
{pud,pmd}_pfn() without checking for CONFIG_TRANSPARENT_HUGEPAGE.  This
works fine on x86, the only arch with devmap support, since the *_pfn()
functions are always defined there, but this isn't true for every
architecture.

Link: http://lkml.kernel.org/r/20170626063833.11094-1-oohall@gmail.com
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-06 17:27:26 -07:00
Punit Agrawal
d63206ee32 mm, gup: ensure real head page is ref-counted when using hugepages
When speculatively taking references to a hugepage using
page_cache_add_speculative() in gup_huge_pmd(), it is assumed that the
page returned by pmd_page() is the head page.  Although normally true,
this assumption doesn't hold when the hugepage comprises of successive
page table entries such as when using contiguous bit on arm64 at PTE or
PMD levels.

This can be addressed by ensuring that the page passed to
page_cache_add_speculative() is the real head or by de-referencing the
head page within the function.

We take the first approach to keep the usage pattern aligned with
page_cache_get_speculative() where users already pass the appropriate
page, i.e., the de-referenced head.

Apply the same logic to fix gup_huge_[pud|pgd]() as well.

[punit.agrawal@arm.com: fix arm64 ltp failure]
  Link: http://lkml.kernel.org/r/20170619170145.25577-5-punit.agrawal@arm.com
Link: http://lkml.kernel.org/r/20170522133604.11392-3-punit.agrawal@arm.com
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Steve Capper <steve.capper@arm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06 16:24:34 -07:00
Will Deacon
a3e328556d mm, gup: remove broken VM_BUG_ON_PAGE compound check for hugepages
When operating on hugepages with DEBUG_VM enabled, the GUP code checks
the compound head for each tail page prior to calling
page_cache_add_speculative.  This is broken, because on the fast-GUP
path (where we don't hold any page table locks) we can be racing with a
concurrent invocation of split_huge_page_to_list.

split_huge_page_to_list deals with this race by using page_ref_freeze to
freeze the page and force concurrent GUPs to fail whilst the component
pages are modified.  This modification includes clearing the
compound_head field for the tail pages, so checking this prior to a
successful call to page_cache_add_speculative can lead to false
positives: In fact, page_cache_add_speculative *already* has this check
once the page refcount has been successfully updated, so we can simply
remove the broken calls to VM_BUG_ON_PAGE.

Link: http://lkml.kernel.org/r/20170522133604.11392-2-punit.agrawal@arm.com
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Steve Capper <steve.capper@arm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06 16:24:34 -07:00
Aneesh Kumar K.V
4dc71451a2 mm/follow_page_mask: add support for hugepage directory entry
Architectures like ppc64 supports hugepage size that is not mapped to
any of of the page table levels.  Instead they add an alternate page
table entry format called hugepage directory (hugepd).  hugepd indicates
that the page table entry maps to a set of hugetlb pages.  Add support
for this in generic follow_page_mask code.  We already support this
format in the generic gup code.

The default implementation prints warning and returns NULL.  We will add
ppc64 support in later patches

Link: http://lkml.kernel.org/r/1494926612-23928-7-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Mike Kravetz <kravetz@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06 16:24:33 -07:00
Anshuman Khandual
faaa5b62d3 mm/follow_page_mask: add support for hugetlb pgd entries
ppc64 supports pgd hugetlb entries.  Add code to handle hugetlb pgd
entries to follow_page_mask so that ppc64 can switch to it to handle
hugetlbe entries.

Link: http://lkml.kernel.org/r/1494926612-23928-5-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Mike Kravetz <kravetz@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06 16:24:33 -07:00
Aneesh Kumar K.V
080dbb618b mm/follow_page_mask: split follow_page_mask to smaller functions.
Makes code reading easy.  No functional changes in this patch.  In a
followup patch, we will be updating the follow_page_mask to handle
hugetlb hugepd format so that archs like ppc64 can switch to the generic
version.  This split helps in doing that nicely.

Link: http://lkml.kernel.org/r/1494926612-23928-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Mike Kravetz <kravetz@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06 16:24:33 -07:00
Ingo Molnar
a4eb8b9935 Merge branch 'linus' into x86/mm, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-22 10:57:28 +02:00
Hugh Dickins
1be7107fbe mm: larger stack guard gap, between vmas
Stack guard page is a useful feature to reduce a risk of stack smashing
into a different mapping. We have been using a single page gap which
is sufficient to prevent having stack adjacent to a different mapping.
But this seems to be insufficient in the light of the stack usage in
userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
which is 256kB or stack strings with MAX_ARG_STRLEN.

This will become especially dangerous for suid binaries and the default
no limit for the stack size limit because those applications can be
tricked to consume a large portion of the stack and a single glibc call
could jump over the guard page. These attacks are not theoretical,
unfortunatelly.

Make those attacks less probable by increasing the stack guard gap
to 1MB (on systems with 4k pages; but make it depend on the page size
because systems with larger base pages might cap stack allocations in
the PAGE_SIZE units) which should cover larger alloca() and VLA stack
allocations. It is obviously not a full fix because the problem is
somehow inherent, but it should reduce attack space a lot.

One could argue that the gap size should be configurable from userspace,
but that can be done later when somebody finds that the new 1MB is wrong
for some special case applications.  For now, add a kernel command line
option (stack_guard_gap) to specify the stack gap size (in page units).

Implementation wise, first delete all the old code for stack guard page:
because although we could get away with accounting one extra page in a
stack vma, accounting a larger gap can break userspace - case in point,
a program run with "ulimit -S -v 20000" failed when the 1MB gap was
counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
and strict non-overcommit mode.

Instead of keeping gap inside the stack vma, maintain the stack guard
gap as a gap between vmas: using vm_start_gap() in place of vm_start
(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
places which need to respect the gap - mainly arch_get_unmapped_area(),
and and the vma tree's subtree_gap support for that.

Original-patch-by: Oleg Nesterov <oleg@redhat.com>
Original-patch-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-19 21:50:20 +08:00
Kirill A. Shutemov
e585513b76 x86/mm/gup: Switch GUP to the generic get_user_page_fast() implementation
This patch provides all required callbacks required by the generic
get_user_pages_fast() code and switches x86 over - and removes
the platform specific implementation.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170606113133.22974-2-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-13 08:56:50 +02:00
James Morse
9a291a7c94 mm/hugetlb: report -EHWPOISON not -EFAULT when FOLL_HWPOISON is specified
KVM uses get_user_pages() to resolve its stage2 faults.  KVM sets the
FOLL_HWPOISON flag causing faultin_page() to return -EHWPOISON when it
finds a VM_FAULT_HWPOISON.  KVM handles these hwpoison pages as a
special case.  (check_user_page_hwpoison())

When huge pages are involved, this doesn't work so well.
get_user_pages() calls follow_hugetlb_page(), which stops early if it
receives VM_FAULT_HWPOISON from hugetlb_fault(), eventually returning
-EFAULT to the caller.  The step to map this to -EHWPOISON based on the
FOLL_ flags is missing.  The hwpoison special case is skipped, and
-EFAULT is returned to user-space, causing Qemu or kvmtool to exit.

Instead, move this VM_FAULT_ to errno mapping code into a header file
and use it from faultin_page() and follow_hugetlb_page().

With this, KVM works as expected.

This isn't a problem for arm64 today as we haven't enabled
MEMORY_FAILURE, but I can't see any reason this doesn't happen on x86
too, so I think this should be a fix.  This doesn't apply earlier than
stable's v4.11.1 due to all sorts of cleanup.

[james.morse@arm.com: add vm_fault_to_errno() call to faultin_page()]
suggested.
  Link: http://lkml.kernel.org/r/20170525171035.16359-1-james.morse@arm.com
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170524160900.28786-1-james.morse@arm.com
Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org>	[4.11.1+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-02 15:07:38 -07:00
Arnd Bergmann
aa2369f11f mm/gup.c: fix access_ok() argument type
MIPS just got changed to only accept a pointer argument for access_ok(),
causing one warning in drivers/scsi/pmcraid.c.  I tried changing x86 the
same way and found the same warning in __get_user_pages_fast() and
nowhere else in the kernel during randconfig testing:

  mm/gup.c: In function '__get_user_pages_fast':
  mm/gup.c:1578:6: error: passing argument 1 of '__chk_range_not_ok' makes pointer from integer without a cast [-Werror=int-conversion]

It would probably be a good idea to enforce type-safety in general, so
let's change this file to not cause a warning if we do that.

I don't know why the warning did not appear on MIPS.

Fixes: 2667f50e8b ("mm: introduce a general RCU get_user_pages_fast()")
Link: http://lkml.kernel.org/r/20170421162659.3314521-1-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-03 15:52:12 -07:00
Ingo Molnar
6dd29b3df9 Revert "x86/mm/gup: Switch GUP to the generic get_user_page_fast() implementation"
This reverts commit 2947ba054a.

Dan Williams reported dax-pmem kernel warnings with the following signature:

   WARNING: CPU: 8 PID: 245 at lib/percpu-refcount.c:155 percpu_ref_switch_to_atomic_rcu+0x1f5/0x200
   percpu ref (dax_pmem_percpu_release [dax_pmem]) <= 0 (0) after switching to atomic

... and bisected it to this commit, which suggests possible memory corruption
caused by the x86 fast-GUP conversion.

He also pointed out:

 "
  This is similar to the backtrace when we were not properly handling
  pud faults and was fixed with this commit: 220ced1676 "mm: fix
  get_user_pages() vs device-dax pud mappings"

  I've found some missing _devmap checks in the generic
  get_user_pages_fast() path, but this does not fix the regression
  [...]
 "

So given that there are known bugs, and a pretty robust looking bisection
points to this commit suggesting that are unknown bugs in the conversion
as well, revert it for the time being - we'll re-try in v4.13.

Reported-by: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: aneesh.kumar@linux.vnet.ibm.com
Cc: dann.frazier@canonical.com
Cc: dave.hansen@intel.com
Cc: steve.capper@linaro.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-04-23 11:45:20 +02:00
Kirill A. Shutemov
2947ba054a x86/mm/gup: Switch GUP to the generic get_user_page_fast() implementation
This patch provides all required callbacks required by the generic
get_user_pages_fast() code and switches x86 over - and removes
the platform specific implementation.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K . V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170316213906.89528-1-kirill.shutemov@linux.intel.com
[ Minor readability edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-18 09:48:03 +01:00
Kirill A. Shutemov
73e10a6181 mm/gup: Provide callback to check if __GUP_fast() is allowed for the range
This is a preparation patch for the transition of x86 to the generic GUP_fast()
implementation.

On x86, get_user_pages_fast() does a couple of sanity checks to see if we can
call __get_user_pages_fast() for the range.

This kind of wrapping protection should be useful for the generic code too.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K . V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170316152655.37789-7-kirill.shutemov@linux.intel.com
[ Small readability edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-18 09:48:03 +01:00
Kirill A. Shutemov
b59f65fa07 mm/gup: Implement the dev_pagemap() logic in the generic get_user_pages_fast() function
This is a preparation patch for the transition of x86 to the generic GUP_fast()
implementation.

Prepare generic GUP_fast() to handle dev_pagemap(). At the moment, it's
only implemented on x86. On non-x86, the new code will be compiled out.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K . V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170316152655.37789-6-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-18 09:48:02 +01:00
Kirill A. Shutemov
e93480537f mm/gup: Mark all pages PageReferenced in generic get_user_pages_fast()
This is a preparation patch for the transition of x86 to the generic GUP_fast()
implementation.

Unlike generic GUP_fast(), the x86 version makes all pages it touches
referenced. It seems required for GRU and EPT.

See the following commit:

  8ee53820ed ("thp: mmu_notifier_test_young")

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K . V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170316152655.37789-5-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-18 09:48:02 +01:00
Kirill A. Shutemov
0005d20b2f mm/gup: Move page table entry dereference into helper function
This is a preparation patch for the transition of x86 to the generic GUP_fast()
implementation.

On x86 PAE, page table entry is larger than sizeof(long) and we would
need to provide a helper that can read the entry atomically.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K . V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170316152655.37789-4-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-18 09:48:02 +01:00
Kirill A. Shutemov
e7884f8ead mm/gup: Move permission checks into helpers
This is a preparation patch for the transition of x86 to the generic GUP_fast()
implementation.

On x86, we would need to do additional permission checks to determine if
access is allowed.

Let's abstract it out into separate helpers.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K . V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170316152655.37789-3-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-18 09:48:01 +01:00
Kirill A. Shutemov
9a804fecee mm/gup: Drop the arch_pte_access_permitted() MMU callback
The only arch that defines it to something meaningful is x86.
But x86 doesn't use the generic GUP_fast() implementation -- the
only place where the callback is called.

Let's drop it.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K . V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170316152655.37789-2-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-18 09:48:01 +01:00
Kirill A. Shutemov
ce70df0891 mm, gup: fix typo in gup_p4d_range()
gup_p4d_range() should call gup_pud_range(), not itself.

[ This was not noticed on x86: this is the HAVE_GENERIC_RCU_GUP code
  used by arm[64] and powerpc    - Linus ]

Fixes: c2febafc67 ("mm: convert generic code to 5-level paging")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Reported-by: Anton Blanchard <anton@samba.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-03-13 08:58:09 -07:00
Kirill A. Shutemov
c2febafc67 mm: convert generic code to 5-level paging
Convert all non-architecture-specific code to 5-level paging.

It's mostly mechanical adding handling one more page table level in
places where we deal with pud_t.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-03-09 11:48:47 -08:00