Patch series "mm / virtio: Provide support for free page reporting", v17.
This series provides an asynchronous means of reporting free guest pages
to a hypervisor so that the memory associated with those pages can be
dropped and reused by other processes and/or guests on the host. Using
this it is possible to avoid unnecessary I/O to disk and greatly improve
performance in the case of memory overcommit on the host.
When enabled we will be performing a scan of free memory every 2 seconds
while pages of sufficiently high order are being freed. In each pass at
least one sixteenth of each free list will be reported. By doing this we
avoid racing against other threads that may be causing a high amount of
memory churn.
The lowest page order currently scanned when reporting pages is
pageblock_order so that this feature will not interfere with the use of
Transparent Huge Pages in the case of virtualization.
Currently this is only in use by virtio-balloon however there is the hope
that at some point in the future other hypervisors might be able to make
use of it. In the virtio-balloon/QEMU implementation the hypervisor is
currently using MADV_DONTNEED to indicate to the host kernel that the page
is currently free. It will be zeroed and faulted back into the guest the
next time the page is accessed.
To track if a page is reported or not the Uptodate flag was repurposed and
used as a Reported flag for Buddy pages. We walk though the free list
isolating pages and adding them to the scatterlist until we either
encounter the end of the list or have processed at least one sixteenth of
the pages that were listed in nr_free prior to us starting. If we fill
the scatterlist before we reach the end of the list we rotate the list so
that the first unreported page we encounter is moved to the head of the
list as that is where we will resume after we have freed the reported
pages back into the tail of the list.
Below are the results from various benchmarks. I primarily focused on two
tests. The first is the will-it-scale/page_fault2 test, and the other is
a modified version of will-it-scale/page_fault1 that was enabled to use
THP. I did this as it allows for better visibility into different parts
of the memory subsystem. The guest is running with 32G for RAM on one
node of a E5-2630 v3. The host has had some features such as CPU turbo
disabled in the BIOS.
Test page_fault1 (THP) page_fault2
Name tasks Process Iter STDEV Process Iter STDEV
Baseline 1 1012402.50 0.14% 361855.25 0.81%
16 8827457.25 0.09% 3282347.00 0.34%
Patches Applied 1 1007897.00 0.23% 361887.00 0.26%
16 8784741.75 0.39% 3240669.25 0.48%
Patches Enabled 1 1010227.50 0.39% 359749.25 0.56%
16 8756219.00 0.24% 3226608.75 0.97%
Patches Enabled 1 1050982.00 4.26% 357966.25 0.14%
page shuffle 16 8672601.25 0.49% 3223177.75 0.40%
Patches enabled 1 1003238.00 0.22% 360211.00 0.22%
shuffle w/ RFC 16 8767010.50 0.32% 3199874.00 0.71%
The results above are for a baseline with a linux-next-20191219 kernel,
that kernel with this patch set applied but page reporting disabled in
virtio-balloon, the patches applied and page reporting fully enabled, the
patches enabled with page shuffling enabled, and the patches applied with
page shuffling enabled and an RFC patch that makes used of MADV_FREE in
QEMU. These results include the deviation seen between the average value
reported here versus the high and/or low value. I observed that during
the test memory usage for the first three tests never dropped whereas with
the patches fully enabled the VM would drop to using only a few GB of the
host's memory when switching from memhog to page fault tests.
Any of the overhead visible with this patch set enabled seems due to page
faults caused by accessing the reported pages and the host zeroing the
page before giving it back to the guest. This overhead is much more
visible when using THP than with standard 4K pages. In addition page
shuffling seemed to increase the amount of faults generated due to an
increase in memory churn. The overehad is reduced when using MADV_FREE as
we can avoid the extra zeroing of the pages when they are reintroduced to
the host, as can be seen when the RFC is applied with shuffling enabled.
The overall guest size is kept fairly small to only a few GB while the
test is running. If the host memory were oversubscribed this patch set
should result in a performance improvement as swapping memory in the host
can be avoided.
A brief history on the background of free page reporting can be found at:
https://lore.kernel.org/lkml/29f43d5796feed0dec8e8bb98b187d9dac03b900.camel@linux.intel.com/
This patch (of 9):
Move the head/tail adding logic out of the shuffle code and into the
__free_one_page function since ultimately that is where it is really
needed anyway. By doing this we should be able to reduce the overhead and
can consolidate all of the list addition bits in one spot.
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: wei qi <weiqi4@huawei.com>
Link: http://lkml.kernel.org/r/20200211224602.29318.84523.stgit@localhost.localdomain
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some comments for MADV_FREE is revised and added to help people understand
the MADV_FREE code, especially the page flag, PG_swapbacked. This makes
page_is_file_cache() isn't consistent with its comments. So the function
is renamed to page_is_file_lru() to make them consistent again. All these
are put in one patch as one logical change.
Suggested-by: David Hildenbrand <david@redhat.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: David Rientjes <rientjes@google.com>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@kernel.org>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/20200317100342.2730705-1-ying.huang@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This updates get_user_pages()'s argument in ksm_test_exit()'s comment
Signed-off-by: Li Chen <chenli@uniontech.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/30ac2417-f1c7-f337-0beb-df561295298c@uniontech.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit e496cf3d78 ("thp: introduce CONFIG_TRANSPARENT_HUGE_PAGECACHE")
notes that it should be reverted when the PowerPC problem was fixed. The
commit fixing the PowerPC problem (953c66c2b2) did not revert the
commit; instead setting CONFIG_TRANSPARENT_HUGE_PAGECACHE to the same as
CONFIG_TRANSPARENT_HUGEPAGE. Checking with Kirill and Aneesh, this was an
oversight, so remove the Kconfig symbol and undo the work of commit
e496cf3d78.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Link: http://lkml.kernel.org/r/20200318140253.6141-6-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If THP is disabled, find_subpage() can become a no-op by using
hpage_nr_pages() instead of compound_nr(). hpage_nr_pages() embeds a
check for PageTail, so we can drop the check here.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Link: http://lkml.kernel.org/r/20200318140253.6141-5-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The thp_fault_fallback and thp_file_fallback vmstats are incremented if
either the hugepage allocation fails through the page allocator or the
hugepage charge fails through mem cgroup.
This patch leaves this field untouched but adds two new fields,
thp_{fault,file}_fallback_charge, which is incremented only when the mem
cgroup charge fails.
This distinguishes between attempted hugepage allocations that fail due to
fragmentation (or low memory conditions) and those that fail due to mem
cgroup limits. That can be used to determine the impact of fragmentation
on the system by excluding faults that failed due to memcg usage.
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Jeremy Cline <jcline@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.2003061422070.7412@chino.kir.corp.google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The existing thp_fault_fallback indicates when thp attempts to allocate a
hugepage but fails, or if the hugepage cannot be charged to the mem cgroup
hierarchy.
Extend this to shmem as well. Adds a new thp_file_fallback to complement
thp_file_alloc that gets incremented when a hugepage is attempted to be
allocated but fails, or if it cannot be charged to the mem cgroup
hierarchy.
Additionally, remove the check for CONFIG_TRANSPARENT_HUGE_PAGECACHE from
shmem_alloc_hugepage() since it is only called with this configuration
option.
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Jeremy Cline <jcline@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.2003061421240.7412@chino.kir.corp.google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently the migration code doesn't migrate PG_readahead flag.
Theoretically this would incur slight performance loss as the application
might have to ramp its readahead back up again. Even though such problem
happens, it might be hidden by something else since migration is typically
triggered by compaction and NUMA balancing, any of which should be more
noticeable.
Migrate the flag after end_page_writeback() since it may clear PG_reclaim
flag, which is the same bit as PG_readahead, for the new page.
[akpm@linux-foundation.org: tweak comment]
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Link: http://lkml.kernel.org/r/1581640185-95731-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It can currently happen that we store the status of a page twice:
* Once we detect that it is already on the target node
* Once we moved a bunch of pages, and a page that's already on the
target node is contained in the current interval.
Let's simplify the code and always call do_move_pages_to_node() in case we
did not queue a page for migration. Note that pages that are already on
the target node are not added to the pagelist and are, therefore, ignored
by do_move_pages_to_node() - there is no functional change.
The status of such a page is now only stored once.
[david@redhat.com rephrase changelog]
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Link: http://lkml.kernel.org/r/20200214003017.25558-5-richardw.yang@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When pagelist is empty, it is not necessary to do the move and store.
Also it consolidate the empty list check in one place.
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Link: http://lkml.kernel.org/r/20200214003017.25558-4-richardw.yang@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Usually, do_move_pages_to_node() and store_status() are used in
combination. We have three similar call sites.
Let's provide a wrapper for both function calls -
move_pages_and_store_status - to make the calling code easier to maintain
and fix (as noted by Yang Shi, the return value handling of
do_move_pages_to_node() has a flaw).
[david@redhat.com rephrase changelog]
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Link: http://lkml.kernel.org/r/20200214003017.25558-3-richardw.yang@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "cleanup on do_pages_move()", v5.
The logic in do_pages_move() is a little mess for audience to read and has
some potential error on handling the return value. Especially there are
three calls on do_move_pages_to_node() and store_status() with almost the
same form.
This patch set tries to make the code a little friendly for audience by
consolidate the calls.
This patch (of 4):
At this point, we always have i >= start. If i == start, store_status()
will return 0. So we can drop the check for i > start.
[david@redhat.com rephrase changelog]
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Link: http://lkml.kernel.org/r/20200214003017.25558-2-richardw.yang@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While it might be really clear to MM developers that gfp reclaim modifiers
are applicable only to sleepable allocations (those with
__GFP_DIRECT_RECLAIM) it seems that actual users of the API are not always
sure. Make it explicit that they are not applicable for GFP_NOWAIT or
GFP_ATOMIC allocations which are the most commonly used non-sleepable
allocation masks.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Neil Brown <neilb@suse.de>
Link: http://lkml.kernel.org/r/20200403083543.11552-3-mhocko@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a typo in comment, fix it.
"exeeds" -> "exceeds"
Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200404060136.10838-1-hqjagain@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It is unlikely that an inaccessible VMA without required permission flags
will get a page fault. Hence lets just append unlikely() directive to
such checks in order to improve performance while also standardizing it
across various platforms.
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Link: http://lkml.kernel.org/r/1582525304-32113-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/vma: Use all available wrappers when possible", v2.
Apart from adding a VMA flag readable name for trace purpose, this series
does some open encoding replacements with availabe VMA specific wrappers.
This skips VM_HUGETLB check in vma_migratable() as its already being done
with another patch (https://patchwork.kernel.org/patch/11347831/) which is
yet to be merged.
This patch (of 4):
This just adds the missing readable name for VM_SYNC.
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/1582520593-30704-2-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Set ->vm_next and ->vm_prev to NULL to prevent potential misuse from the
new duplicated vma.
Currently, only in fork path there are misuse for handling anon_vma. No
other bugs been revealed with this patch applied.
Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Link: http://lkml.kernel.org/r/1581150928-3214-4-git-send-email-lixinhai.lxh@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit 4e4a9eb921 ("mm/rmap.c: reuse mergeable
anon_vma as parent when fork").
In dup_mmap(), anon_vma_fork() is called for attaching anon_vma and
parameter 'tmp' (i.e., the new vma of child) has same ->vm_next and
->vm_prev as its parent vma. That causes the anon_vma used by parent been
mistakenly shared by child (In anon_vma_clone(), the code added by that
commit will do this reuse work).
Besides this issue, the design of reusing anon_vma from vma which has gone
through fork should be avoided ([1]). So, this patch reverts that commit
and maintains the consistent logic of reusing anon_vma for
fork/split/merge vma.
Reusing anon_vma within the process is fine. But if a vma has gone
through fork(), then that vma's anon_vma should not be shared with its
neighbor vma. As explained in [1], when vma gone through fork(), the
check for list_is_singular(vma->anon_vma_chain) will be false, and
don't share anon_vma.
With current issue, one example can clarify more. Parent process do
below two steps:
1. p_vma_1 is created and p_anon_vma_1 is prepared;
2. p_vma_2 is created and share p_anon_vma_1; (this is allowed,
becaues p_vma_1 didn't gothrough fork()); parent process do fork():
3. c_vma_1 is dup from p_vma_1, and has its own c_anon_vma_1
prepared; at this point, c_vma_1->anon_vma_chain has two items, one
for p_anon_vma_1 and one for c_anon_vma_1;
4. c_vma_2 is dup from p_vma_2, it is not allowed to share
c_anon_vma_1, because
c_vma_1->anon_vma_chain has two items.
[1] commit d0e9fe1758 ("Simplify and comment on anon_vma re-use for
anon_vma_prepare()") explains the test of "list_is_singular()".
Fixes: 4e4a9eb921 ("mm/rmap.c: reuse mergeable anon_vma as parent when fork")
Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Link: http://lkml.kernel.org/r/1581150928-3214-3-git-send-email-lixinhai.lxh@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: Fix misuse of parent anon_vma in dup_mmap path".
This patchset fixes the misuse of parenet anon_vma, which mainly caused by
child vma's vm_next and vm_prev are left same as its parent after
duplicate vma. Finally, code reached parent vma's neighbor by referring
pointer of child vma and executed wrong logic.
The first two patches fix relevant issues, and the third patch sets
vm_next and vm_prev to NULL when duplicate vma to prevent potential misuse
in future.
Effects of the first bug is that causes rmap code to check both parent and
child's page table, although a page couldn't be mapped by both parent and
child, because child vma has WIPEONFORK so all pages mapped by child are
'new' and not relevant to parent.
Effects of the second bug is that the relationship of anon_vma of parent
and child are totallyconvoluted. It would cause 'son', 'grandson', ...,
etc, to share 'parent' anon_vma, which disobey the design rule of reusing
anon_vma (the rule to be followed is that reusing should among vma of same
process, and vma should not gone through fork).
So, both issues should cause unnecessary rmap walking and have unexpected
complexity.
These two issues would not be directly visible, I used debugging code to
check the anon_vma pointers of parent and child when inspecting the
suspicious implementation of issue #2, then find the problem.
This patch (of 3):
In dup_mmap(), anon_vma_prepare() is called for vma has VM_WIPEONFORK, and
parameter 'tmp' (i.e., the new vma of child) has same ->vm_next and
->vm_prev as its parent vma. That allows anon_vma used by parent been
mistakenly shared by child (find_mergeable_anon_vma() will do this reuse
work).
Besides this issue, call anon_vma_prepare() should be avoided because we
don't copy page for this vma. Preparing anon_vma will be handled during
fault.
Fixes: d2cd9ede6e ("mm,fork: introduce MADV_WIPEONFORK")
Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Link: http://lkml.kernel.org/r/1581150928-3214-2-git-send-email-lixinhai.lxh@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The root of the hierarchy cannot have high set, so we will never reclaim
based on it. This makes that clearer and avoids another entry.
Signed-off-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Link: http://lkml.kernel.org/r/20200312164137.GA1753625@chrisdown.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Immediate packets should only be sent to peer when there are new
receive credits made available. New credits show up on freeing
receive buffer, not on receiving data.
Fix this by avoid unnenecessary work schedules.
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
When processing errors from ib_post_send(), the transport state needs to be
rolled back to the condition before the error.
Refactor the old code to make it easy to roll back on IB errors, and fix this.
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CIFS uses pre-allocated crypto structures to calculate signatures for both
incoming and outgoing packets. In this way it doesn't need to allocate crypto
structures for every packet, but it requires a lock to prevent concurrent
access to crypto structures.
Remove the lock by allocating crypto structures on the fly for
incoming packets. At the same time, we can still use pre-allocated crypto
structures for outgoing packets, as they are already protected by transport
lock srv_mutex.
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Recevie credits should be updated before sending the packet, not
before a work is scheduled. Also, the value needs roll back if
something fails and cannot send.
Signed-off-by: Long Li <longli@microsoft.com>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Sometimes the remote peer may return more send credits than the send queue
depth. If all the send credits are used to post senasd, we may overflow the
send queue.
Fix this by checking the send queue size before posting a send.
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
As an optimization, SMBD tries to track two types of packets: packets with
payload and without payload. There is no obvious benefit or performance gain
to separately track two types of packets.
Just treat them as pending packets and merge the tracking code.
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Fix tcon use-after-free and NULL ptr deref.
Customer system crashes with the following kernel log:
[462233.169868] CIFS VFS: Cancelling wait for mid 4894753 cmd: 14 => a QUERY DIR
[462233.228045] CIFS VFS: cifs_put_smb_ses: Session Logoff failure rc=-4
[462233.305922] CIFS VFS: cifs_put_smb_ses: Session Logoff failure rc=-4
[462233.306205] CIFS VFS: cifs_put_smb_ses: Session Logoff failure rc=-4
[462233.347060] CIFS VFS: cifs_put_smb_ses: Session Logoff failure rc=-4
[462233.347107] CIFS VFS: Close unmatched open
[462233.347113] BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
...
[exception RIP: cifs_put_tcon+0xa0] (this is doing tcon->ses->server)
#6 [...] smb2_cancelled_close_fid at ... [cifs]
#7 [...] process_one_work at ...
#8 [...] worker_thread at ...
#9 [...] kthread at ...
The most likely explanation we have is:
* When we put the last reference of a tcon (refcount=0), we close the
cached share root handle.
* If closing a handle is interrupted, SMB2_close() will
queue a SMB2_close() in a work thread.
* The queued object keeps a tcon ref so we bump the tcon
refcount, jumping from 0 to 1.
* We reach the end of cifs_put_tcon(), we free the tcon object despite
it now having a refcount of 1.
* The queued work now runs, but the tcon, ses & server was freed in
the meantime resulting in a crash.
THREAD 1
========
cifs_put_tcon => tcon refcount reach 0
SMB2_tdis
close_shroot_lease
close_shroot_lease_locked => if cached root has lease && refcount = 0
smb2_close_cached_fid => if cached root valid
SMB2_close => retry close in a thread if interrupted
smb2_handle_cancelled_close
__smb2_handle_cancelled_close => !! tcon refcount bump 0 => 1 !!
INIT_WORK(&cancelled->work, smb2_cancelled_close_fid);
queue_work(cifsiod_wq, &cancelled->work) => queue work
tconInfoFree(tcon); ==> freed!
cifs_put_smb_ses(ses); ==> freed!
THREAD 2 (workqueue)
========
smb2_cancelled_close_fid
SMB2_close(0, cancelled->tcon, ...); => use-after-free of tcon
cifs_put_tcon(cancelled->tcon); => tcon refcount reach 0 second time
*CRASH*
Fixes: d919131935 ("CIFS: Close cached root handle only if it has a lease")
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
In case rdma accept fails at nvmet_rdma_queue_connect(), release work is
scheduled. Later on, a new RDMA CM event may arrive since we didn't
destroy the cm-id and call nvmet_rdma_queue_connect_fail(), which
schedule another release work. This will cause calling
nvmet_rdma_free_queue twice. To fix this we implicitly destroy the cm_id
with non-zero ret code, which guarantees that new rdma_cm events will
not arrive afterwards. Also add a qp pointer to nvmet_rdma_queue
structure, so we can use it when the cm_id pointer is NULL or was
destroyed.
Signed-off-by: Israel Rukshin <israelr@mellanox.com>
Suggested-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
An earlier commit "io_uring: remove @nxt from handlers" removed the
setting of pointer nxt and now it is always null, hence the non-null
check and call to io_wq_assign_next is redundant and can be removed.
Addresses-Coverity: ("'Constant' variable guard")
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The access to Analog Capture Source control value implemented in
prodigy_hifi.c is wrong, as caught by the recently introduced sanity
check; it should be accessing value.enumerated.item[] instead of
value.integer.value[]. This patch corrects the wrong access pattern.
Fixes: 6b8d6e5518 ("[ALSA] ICE1724: Added support for Audiotrak Prodigy 7.1 HiFi & HD2, Hercules Fortissimo IV")
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=207139
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200407084402.25589-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
The beep control helper function blindly stores the values in two
stereo channels no matter whether the actual control is mono or
stereo. This is practically harmless, but it annoys the recently
introduced sanity check, resulting in an error when the checker is
enabled.
This patch corrects the behavior to store only on the defined array
member.
Fixes: 0401e8548e ("ALSA: hda - Move beep helper functions to hda_beep.c")
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=207139
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200407084402.25589-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Pull the RST line low then high when initializing the driver,
in order to force a reset of the chip.
Previously, the line was not pulled low, which could result in
the chip registers not resetting to their default values on boot.
Signed-off-by: Mike Willard <mwillard@izotope.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200401205454.79792-1-mwillard@izotope.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This needs to return the newly allocated struct but instead it returns
zero which leads to an immediate Oops in the caller.
Fixes: 09f5f68070 ("ipmi: kcs: aspeed: Implement v2 bindings")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Message-Id: <20200407122149.GA100026@mwanda>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
If KVM wasn't used at all before we crash the cleanup procedure fails with
BUG: unable to handle page fault for address: ffffffffffffffc8
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 23215067 P4D 23215067 PUD 23217067 PMD 0
Oops: 0000 [#8] SMP PTI
CPU: 0 PID: 3542 Comm: bash Kdump: loaded Tainted: G D 5.6.0-rc2+ #823
RIP: 0010:crash_vmclear_local_loaded_vmcss.cold+0x19/0x51 [kvm_intel]
The root cause is that loaded_vmcss_on_cpu list is not yet initialized,
we initialize it in hardware_enable() but this only happens when we start
a VM.
Previously, we used to have a bitmap with enabled CPUs and that was
preventing [masking] the issue.
Initialized loaded_vmcss_on_cpu list earlier, right before we assign
crash_vmclear_loaded_vmcss pointer. blocked_vcpu_on_cpu list and
blocked_vcpu_on_cpu_lock are moved altogether for consistency.
Fixes: 31603d4fc2 ("KVM: VMX: Always VMCLEAR in-use VMCSes during crash with kexec support")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200401081348.1345307-1-vkuznets@redhat.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Except destination shorthand, a destination value 0xffffffff is used to
broadcast interrupts, let's also filter out this for single target IPI
fastpath.
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1585815626-28370-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- Several fixes for corner cases of nesting. Still relevant as it might
crash host or first level guest or temporarily leak memory.
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Merge tag 'kvm-s390-master-5.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD
KVM: s390: Fixes for vsie (nested hypervisors)
- Several fixes for corner cases of nesting. Still relevant as it might
crash host or first level guest or temporarily leak memory.
We have to properly retry again by returning -EINVAL immediately in case
somebody else instantiated the table concurrently. We missed to add the
goto in this function only. The code now matches the other, similar
shadowing functions.
We are overwriting an existing region 2 table entry. All allocated pages
are added to the crst_list to be freed later, so they are not lost
forever. However, when unshadowing the region 2 table, we wouldn't trigger
unshadowing of the original shadowed region 3 table that we replaced. It
would get unshadowed when the original region 3 table is modified. As it's
not connected to the page table hierarchy anymore, it's not going to get
used anymore. However, for a limited time, this page table will stick
around, so it's in some sense a temporary memory leak.
Identified by manual code inspection. I don't think this classifies as
stable material.
Fixes: 998f637cc4 ("s390/mm: avoid races on region/segment/page table shadowing")
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20200403153050.20569-4-david@redhat.com
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Whenever we get an -EFAULT, we failed to read in guest 2 physical
address space. Such addressing exceptions are reported via a program
intercept to the nested hypervisor.
We faked the intercept, we have to return to guest 2. Instead, right
now we would be returning -EFAULT from the intercept handler, eventually
crashing the VM.
the correct thing to do is to return 1 as rc == 1 is the internal
representation of "we have to go back into g2".
Addressing exceptions can only happen if the g2->g3 page tables
reference invalid g2 addresses (say, either a table or the final page is
not accessible - so something that basically never happens in sane
environments.
Identified by manual code inspection.
Fixes: a3508fbe9d ("KVM: s390: vsie: initial support for nested virtualization")
Cc: <stable@vger.kernel.org> # v4.8+
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20200403153050.20569-3-david@redhat.com
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
[borntraeger@de.ibm.com: fix patch description]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
In case we have a region 1 the following calculation
(31 + ((gmap->asce & _ASCE_TYPE_MASK) >> 2)*11)
results in 64. As shifts beyond the size are undefined the compiler is
free to use instructions like sllg. sllg will only use 6 bits of the
shift value (here 64) resulting in no shift at all. That means that ALL
addresses will be rejected.
The can result in endless loops, e.g. when prefix cannot get mapped.
Fixes: 4be130a084 ("s390/mm: add shadow gmap support")
Tested-by: Janosch Frank <frankja@linux.ibm.com>
Reported-by: Janosch Frank <frankja@linux.ibm.com>
Cc: <stable@vger.kernel.org> # v4.8+
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20200403153050.20569-2-david@redhat.com
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
[borntraeger@de.ibm.com: fix patch description, remove WARN_ON_ONCE]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Michael noticed that userns limit for number of time namespaces is missing.
Furthermore, time namespace introduced UCOUNT_TIME_NAMESPACES, but didn't
introduce an array member in user_table[]. It would make array's
initialisation OOB write, but by luck the user_table array has an excessive
empty member (all accesses to the array are limited with UCOUNT_COUNTS - so
it silently reuses the last free member.
Fixes user-visible regression: max_inotify_instances by reason of the
missing UCOUNT_ENTRY() has limited max number of namespaces instead of the
number of inotify instances.
Fixes: 769071ac9f ("ns: Introduce Time Namespace")
Reported-by: Michael Kerrisk (man-pages) <mtk.manpages@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andrei Vagin <avagin@gmail.com>
Acked-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: stable@kernel.org
Link: https://lkml.kernel.org/r/20200406171342.128733-1-dima@arista.com
Looking at the contents of the /proc/PID/ns/time_for_children symlink shows
an anomaly:
$ ls -l /proc/self/ns/* |awk '{print $9, $10, $11}'
...
/proc/self/ns/pid -> pid:[4026531836]
/proc/self/ns/pid_for_children -> pid:[4026531836]
/proc/self/ns/time -> time:[4026531834]
/proc/self/ns/time_for_children -> time_for_children:[4026531834]
/proc/self/ns/user -> user:[4026531837]
...
The reference for 'time_for_children' should be a 'time' namespace, just as
the reference for 'pid_for_children' is a 'pid' namespace. In other words,
the above time_for_children link should read:
/proc/self/ns/time_for_children -> time:[4026531834]
Fixes: 769071ac9f ("ns: Introduce Time Namespace")
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dmitry Safonov <dima@arista.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Andrei Vagin <avagin@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/a2418c48-ed80-3afe-116e-6611cb799557@gmail.com
Commit 1d5c76e664 ("xen-blkfront: switch kcalloc to kvcalloc for
large array allocation") didn't fix the issue it was meant to, as the
flags for allocating the memory are GFP_NOIO, which will lead the
memory allocation falling back to kmalloc().
So instead of GFP_NOIO use GFP_KERNEL and do all the memory allocation
in blkfront_setup_indirect() in a memalloc_noio_{save,restore} section.
Fixes: 1d5c76e664 ("xen-blkfront: switch kcalloc to kvcalloc for large array allocation")
Cc: stable@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Link: https://lore.kernel.org/r/20200403090034.8753-1-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Make event channel functions pass event channel port using
evtchn_port_t type. It eliminates signed <-> unsigned conversion.
Signed-off-by: Yan Yankovskyi <yyankovskyi@gmail.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20200323152343.GA28422@kbp1-lhp-F74019
Signed-off-by: Juergen Gross <jgross@suse.com>
This reverts commit 5a6b4cc5b7.
It has been queued properly in the akpm tree, this version is just
creating conflicts.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
When CONFIG_DEVFREQ_THERMAL is disabled all functions except
of_devfreq_cooling_register_power() were already inlined. Also inline
the last function to avoid compile errors when multiple drivers call
of_devfreq_cooling_register_power() when CONFIG_DEVFREQ_THERMAL is not
set. Compilation failed with the following message:
multiple definition of `of_devfreq_cooling_register_power'
(which then lists all usages of of_devfreq_cooling_register_power())
Thomas Zimmermann reported this problem [0] on a kernel config with
CONFIG_DRM_LIMA={m,y}, CONFIG_DRM_PANFROST={m,y} and
CONFIG_DEVFREQ_THERMAL=n after both, the lima and panfrost drivers
gained devfreq cooling support.
[0] https://www.spinics.net/lists/dri-devel/msg252825.html
Fixes: a76caf55e5 ("thermal: Add devfreq cooling")
Cc: stable@vger.kernel.org
Reported-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Tested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200403205133.1101808-1-martin.blumenstingl@googlemail.com
