As Peter points out, the caller passes a single VMA and can just do that
check itself.
And in fact, no existing users rely on test_walk() getting called. So
let's just remove it and make the implementation slightly more efficient.
Link: https://lkml.kernel.org/r/20221021101141.84170-7-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/ksm: break_ksm() cleanups and fixes", v2.
This series cleans up and fixes break_ksm(). In summary, we no longer use
fake write faults to break COW but instead FAULT_FLAG_UNSHARE. Further,
we move away from using follow_page() --- that we can hopefully remove
completely at one point --- and use new walk_page_range_vma() instead.
Fortunately, we can get rid of VM_FAULT_WRITE and FOLL_MIGRATION in common
code now.
Extend the existing ksm tests by an unmerge benchmark, and a some new
unmerge tests.
Also, add a selftest to measure MADV_UNMERGEABLE performance. In my setup
(AMD Ryzen 9 3900X), running the KSM selftest to test unmerge performance
on 2 GiB (taskset 0x8 ./ksm_tests -D -s 2048), this results in a
performance degradation of ~6% -- 7% (old: ~5250 MiB/s, new: ~4900 MiB/s).
I don't think we particularly care for now, but it's good to be aware of
the implication.
This patch (of 9):
Let's add three unmerge tests (MADV_UNMERGEABLE unmerging all pages in the
range).
test_unmerge(): basic unmerge tests
test_unmerge_discarded(): have some pte_none() entries in the range
test_unmerge_uffd_wp(): protect the merged pages using uffd-wp
ksm_tests.c currently contains a mixture of benchmarks and tests, whereby
each test is carried out by executing the ksm_tests binary with specific
parameters. Let's add new ksm_functional_tests.c that performs multiple,
smaller functional tests all at once.
Link: https://lkml.kernel.org/r/20221021101141.84170-1-david@redhat.com
Link: https://lkml.kernel.org/r/20221021101141.84170-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Our memory management kernel CI testing at Red Hat uses the VM
selftests and we have run into two problems:
First, our LTP tests overlap with the VM selftests.
We want to avoid unhelpful redundancy in our testing practices.
Second, we have observed the current run_vmtests.sh to report overall
failure/ambiguous results in the case that a machine lacks the necessary
hardware to perform one or more of the tests. E.g. ksm tests that
require more than one numa node.
We want to be able to run the vm selftests suitable to particular hardware.
Add the ability to run one or more groups of vm tests via run_vmtests.sh
instead of simply all-or-none in order to solve these problems.
Preserve existing default behavior of running all tests when the script
is invoked with no arguments.
Documentation of test groups is included in the patch as follows:
# ./run_vmtests.sh [ -h || --help ]
usage: ./tools/testing/selftests/vm/run_vmtests.sh [ -h | -t "<categories>"]
-t: specify specific categories to tests to run
-h: display this message
The default behavior is to run all tests.
Alternatively, specific groups tests can be run by passing a string
to the -t argument containing one or more of the following categories
separated by spaces:
- mmap
tests for mmap(2)
- gup_test
tests for gup using gup_test interface
- userfaultfd
tests for userfaultfd(2)
- compaction
a test for the patch "Allow compaction of unevictable pages"
- mlock
tests for mlock(2)
- mremap
tests for mremap(2)
- hugevm
tests for very large virtual address space
- vmalloc
vmalloc smoke tests
- hmm
hmm smoke tests
- madv_populate
test memadvise(2) MADV_POPULATE_{READ,WRITE} options
- memfd_secret
test memfd_secret(2)
- process_mrelease
test process_mrelease(2)
- ksm
ksm tests that do not require >=2 NUMA nodes
- ksm_numa
ksm tests that require >=2 NUMA nodes
- pkey
memory protection key tests
- soft_dirty
test soft dirty page bit semantics
- anon_cow
test anonymous copy-on-write semantics
example: ./run_vmtests.sh -t "hmm mmap ksm"
Link: https://lkml.kernel.org/r/20221018231222.1884715-1-jsavitz@redhat.com
Signed-off-by: Joel Savitz <jsavitz@redhat.com>
Cc: Joel Savitz <jsavitz@redhat.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
memcg_write_event_control() accesses the dentry->d_name of the specified
control fd to route the write call. As a cgroup interface file can't be
renamed, it's safe to access d_name as long as the specified file is a
regular cgroup file. Also, as these cgroup interface files can't be
removed before the directory, it's safe to access the parent too.
Prior to 347c4a8747 ("memcg: remove cgroup_event->cft"), there was a
call to __file_cft() which verified that the specified file is a regular
cgroupfs file before further accesses. The cftype pointer returned from
__file_cft() was no longer necessary and the commit inadvertently dropped
the file type check with it allowing any file to slip through. With the
invarients broken, the d_name and parent accesses can now race against
renames and removals of arbitrary files and cause use-after-free's.
Fix the bug by resurrecting the file type check in __file_cft(). Now that
cgroupfs is implemented through kernfs, checking the file operations needs
to go through a layer of indirection. Instead, let's check the superblock
and dentry type.
Link: https://lkml.kernel.org/r/Y5FRm/cfcKPGzWwl@slm.duckdns.org
Fixes: 347c4a8747 ("memcg: remove cgroup_event->cft")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jann Horn <jannh@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: <stable@vger.kernel.org> [3.14+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add more sanity checks to the VMA that do_brk_flags() will expand. Ensure
the VMA matches basic merge requirements within the function before
calling can_vma_merge_after().
Drop the duplicate checks from vm_brk_flags() since they will be enforced
later.
The old code would expand file VMAs on brk(), which is functionally
wrong and also dangerous in terms of locking because the brk() path
isn't designed for file VMAs and therefore doesn't lock the file
mapping. Checking can_vma_merge_after() ensures that new anonymous
VMAs can't be merged into file VMAs.
See https://lore.kernel.org/linux-mm/CAG48ez1tJZTOjS_FjRZhvtDA-STFmdw8PEizPDwMGFd_ui0Nrw@mail.gmail.com/
Link: https://lkml.kernel.org/r/20221205192304.1957418-1-Liam.Howlett@oracle.com
Fixes: 2e7ce7d354 ("mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Suggested-by: Jann Horn <jannh@google.com>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
We use "unsigned long" to store a PFN in the kernel and phys_addr_t to
store a physical address.
On a 64bit system, both are 64bit wide. However, on a 32bit system, the
latter might be 64bit wide. This is, for example, the case on x86 with
PAE: phys_addr_t and PTEs are 64bit wide, while "unsigned long" only spans
32bit.
The current definition of SWP_PFN_BITS without MAX_PHYSMEM_BITS misses
that case, and assumes that the maximum PFN is limited by an 32bit
phys_addr_t. This implies, that SWP_PFN_BITS will currently only be able
to cover 4 GiB - 1 on any 32bit system with 4k page size, which is wrong.
Let's rely on the number of bits in phys_addr_t instead, but make sure to
not exceed the maximum swap offset, to not make the BUILD_BUG_ON() in
is_pfn_swap_entry() unhappy. Note that swp_entry_t is effectively an
unsigned long and the maximum swap offset shares that value with the swap
type.
For example, on an 8 GiB x86 PAE system with a kernel config based on
Debian 11.5 (-> CONFIG_FLATMEM=y, CONFIG_X86_PAE=y), we will currently
fail removing migration entries (remove_migration_ptes()), because
mm/page_vma_mapped.c:check_pte() will fail to identify a PFN match as
swp_offset_pfn() wrongly masks off PFN bits. For example,
split_huge_page_to_list()->...->remap_page() will leave migration entries
in place and continue to unlock the page.
Later, when we stumble over these migration entries (e.g., via
/proc/self/pagemap), pfn_swap_entry_to_page() will BUG_ON() because these
migration entries shouldn't exist anymore and the page was unlocked.
[ 33.067591] kernel BUG at include/linux/swapops.h:497!
[ 33.067597] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
[ 33.067602] CPU: 3 PID: 742 Comm: cow Tainted: G E 6.1.0-rc8+ #16
[ 33.067605] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014
[ 33.067606] EIP: pagemap_pmd_range+0x644/0x650
[ 33.067612] Code: 00 00 00 00 66 90 89 ce b9 00 f0 ff ff e9 ff fb ff ff 89 d8 31 db e8 48 c6 52 00 e9 23 fb ff ff e8 61 83 56 00 e9 b6 fe ff ff <0f> 0b bf 00 f0 ff ff e9 38 fa ff ff 3e 8d 74 26 00 55 89 e5 57 31
[ 33.067615] EAX: ee394000 EBX: 00000002 ECX: ee394000 EDX: 00000000
[ 33.067617] ESI: c1b0ded4 EDI: 00024a00 EBP: c1b0ddb4 ESP: c1b0dd68
[ 33.067619] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 EFLAGS: 00010246
[ 33.067624] CR0: 80050033 CR2: b7a00000 CR3: 01bbbd20 CR4: 00350ef0
[ 33.067625] Call Trace:
[ 33.067628] ? madvise_free_pte_range+0x720/0x720
[ 33.067632] ? smaps_pte_range+0x4b0/0x4b0
[ 33.067634] walk_pgd_range+0x325/0x720
[ 33.067637] ? mt_find+0x1d6/0x3a0
[ 33.067641] ? mt_find+0x1d6/0x3a0
[ 33.067643] __walk_page_range+0x164/0x170
[ 33.067646] walk_page_range+0xf9/0x170
[ 33.067648] ? __kmem_cache_alloc_node+0x2a8/0x340
[ 33.067653] pagemap_read+0x124/0x280
[ 33.067658] ? default_llseek+0x101/0x160
[ 33.067662] ? smaps_account+0x1d0/0x1d0
[ 33.067664] vfs_read+0x90/0x290
[ 33.067667] ? do_madvise.part.0+0x24b/0x390
[ 33.067669] ? debug_smp_processor_id+0x12/0x20
[ 33.067673] ksys_pread64+0x58/0x90
[ 33.067675] __ia32_sys_ia32_pread64+0x1b/0x20
[ 33.067680] __do_fast_syscall_32+0x4c/0xc0
[ 33.067683] do_fast_syscall_32+0x29/0x60
[ 33.067686] do_SYSENTER_32+0x15/0x20
[ 33.067689] entry_SYSENTER_32+0x98/0xf1
Decrease the indentation level of SWP_PFN_BITS and SWP_PFN_MASK to keep it
readable and consistent.
[david@redhat.com: rely on sizeof(phys_addr_t) and min_t() instead]
Link: https://lkml.kernel.org/r/20221206105737.69478-1-david@redhat.com
[david@redhat.com: use "int" for comparison, as we're only comparing numbers < 64]
Link: https://lkml.kernel.org/r/1f157500-2676-7cef-a84e-9224ed64e540@redhat.com
Link: https://lkml.kernel.org/r/20221205150857.167583-1-david@redhat.com
Fixes: 0d206b5d2e ("mm/swap: add swp_offset_pfn() to fetch PFN from swap entry")
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Fix tmpfs data loss when the fallocate system call is interrupted by a
signal, or fails for some other reason. The partial folio handling in
shmem_undo_range() forgot to consider this unfalloc case, and was liable
to erase or truncate out data which had already been committed earlier.
It turns out that none of the partial folio handling there is appropriate
for the unfalloc case, which just wants to proceed to removal of whole
folios: which find_get_entries() provides, even when partially covered.
Original patch by Rui Wang.
Link: https://lore.kernel.org/linux-mm/33b85d82.7764.1842e9ab207.Coremail.chenguoqic@163.com/
Link: https://lkml.kernel.org/r/a5dac112-cf4b-7af-a33-f386e347fd38@google.com
Fixes: b9a8a4195c ("truncate,shmem: Handle truncates that split large folios")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Guoqi Chen <chenguoqic@163.com>
Link: https://lore.kernel.org/all/20221101032248.819360-1-kernel@hev.cc/
Cc: Rui Wang <kernel@hev.cc>
Cc: Huacai Chen <chenhuacai@loongson.cn>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: <stable@vger.kernel.org> [5.17+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
1813e51eec ("memcg: increase MEMCG_CHARGE_BATCH to 64") has changed
the batch size while this test case has been left behind. This has led
to a test failure reported by test bot:
not ok 2 selftests: cgroup: test_kmem # exit=1
Update the tolerance for the pcp charges to reflect the
MEMCG_CHARGE_BATCH change to fix this.
[akpm@linux-foundation.org: update comments, per Roman]
Link: https://lkml.kernel.org/r/Y4m8Unt6FhWKC6IH@dhcp22.suse.cz
Fixes: 1813e51eec ("memcg: increase MEMCG_CHARGE_BATCH to 64")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: kernel test robot <yujie.liu@intel.com>
Link: https://lore.kernel.org/oe-lkp/202212010958.c1053bd3-yujie.liu@intel.com
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Tested-by: Yujie Liu <yujie.liu@intel.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Michal Koutný" <mkoutny@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The email backend used by ROHM keeps labeling patches as spam. This can
result in missing the patches.
Switch my mail address from a company mail to a personal one.
Link: https://lkml.kernel.org/r/8f4498b66fedcbded37b3b87e0c516e659f8f583.1669912977.git.mazziesaccount@gmail.com
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Suggested-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Anup Patel <anup@brainfault.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Atish Patra <atishp@atishpatra.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Ben Widawsky <bwidawsk@kernel.org>
Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Kirill Tkhai <tkhai@ya.ru>
Cc: Qais Yousef <qyousef@layalina.io>
Cc: Vasily Averin <vasily.averin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
If freeit is true, the value of ret must be zero, there is no need to
check the value of freeit after label unlock_mutex.
We can drop variable freeit to do this cleanup.
Link: https://lkml.kernel.org/r/20221125065444.3462681-1-mawupeng1@huawei.com
Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: zhenwei pi <pizhenwei@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
We used to have 624a2c94f5 (Partly revert "mm/thp: carry over dirty bit
when thp splits on pmd") fixing the regression reported here by Anatoly
Pugachev on sparc64:
https://lore.kernel.org/r/20221021160603.GA23307@u164.east.ru
Where we temporarily ignored the dirty bit for small pages.
Then, Hev also reported similar issue on loongarch:
(the original mail was private, but Anatoly copied the list here)
https://lore.kernel.org/r/CADxRZqxqb7f_WhMh=jweZP+ynf_JwGd-0VwbYgp4P+T0-AXosw@mail.gmail.com
Hev pointed out that the issue is having HW write bit set within the
pte_mkdirty() so the split pte can be written after split even if e.g.
they were shared by more than one processes, causing data corrupt.
Hev also tried to explain why loongarch set HW write bit in mkdirty:
https://lore.kernel.org/r/CAHirt9itKO_K_HPboXh5AyJtt16Zf0cD73PtHvM=na39u_ztxA@mail.gmail.com
One way to fix it is as what Huacai proposed here for loongarch (then we
can re-apply the dirty bit in thp split):
https://lore.kernel.org/r/20221117042532.4064448-1-chenhuacai@loongson.cnn
We may need similar thing for sparc64, though.
For now since we've found the root cause of the dirty bit issue the
simpler solution (which won't lose the dirty bit for small) that will work
for both is we wr-protect after pte_mkdirty(), so the HW write bit can be
persistent after thp split.
Add a comment for wrprotect, so we will not mess up the ordering later.
With 624a2c94f5 (Partly revert "mm/thp: carry over dirty bit when thp
splits on pmd") this is not a fix anymore, but just brings back the dirty
bit for thp split safely, so we re-apply the optimization but in safe way.
Provide a Tested-by credit to Hev too (not the exact same patch but the
same outcome) for loongarch.
Link: https://lkml.kernel.org/r/20221125185857.3110155-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Hev <r@hev.cc> # loongarch
Cc: Anatoly Pugachev <matorola@gmail.com>
Cc: Raghavendra K T <raghavendra.kt@amd.com>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Replace open-coded snprintf() with sysfs_emit() to simplify the code.
Link: https://lkml.kernel.org/r/202211241929015476424@zte.com.cn
Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
Signed-off-by: Yang Yang <yang.yang29@zte.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In __gmap_segment_gaddr() pmd level page table page is being extracted
from the pmd pointer, similar to pmd_pgtable_page() implementation. This
reduces some redundancy by directly using pmd_pgtable_page() instead,
though first making it available.
Link: https://lkml.kernel.org/r/20221125034502.1559986-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Current pmd_to_page(), which derives the page table page containing the
pmd address has a very misleading name. The problem being, it sounds
similar to pmd_page() which derives page embedded in a given pmd entry
either for next level page or a mapped huge page. Rename it as
pmd_pgtable_page() instead.
Link: https://lkml.kernel.org/r/20221124131641.1523772-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
zswap_frontswap_load() should be called from preemptible context (we even
call mutex_lock() there) and it does not look like we need to do
GFP_ATOMIC allocaion for temp buffer. The same applies to
zswap_writeback_entry().
Use GFP_KERNEL for temporary buffer allocation in both cases.
Link: https://lkml.kernel.org/r/Y3xCTr6ikbtcUr/y@google.com
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Although pmd_present() might seem to indicate a valid and mapped pmd
entry, in reality it returns true when pmd_page() points to a valid page
in memory , regardless whether the pmd entry is mapped or not. Andrea
Arcangeli had earlier explained [1] the required semantics for
pmd_present(). This just updates the documentation for pmd_present() as
required.
[1] https://lore.kernel.org/lkml/20181017020930.GN30832@redhat.com/
Link: https://lkml.kernel.org/r/20221123051319.1312582-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Depending on the memory configuration, isolate_freepages_block() may scan
pages out of the target range and causes panic.
Panic can occur on systems with multiple zones in a single pageblock.
The reason it is rare is that it only happens in special
configurations. Depending on how many similar systems there are, it
may be a good idea to fix this problem for older kernels as well.
The problem is that pfn as argument of fast_isolate_around() could be out
of the target range. Therefore we should consider the case where pfn <
start_pfn, and also the case where end_pfn < pfn.
This problem should have been addressd by the commit 6e2b7044c1 ("mm,
compaction: make fast_isolate_freepages() stay within zone") but there was
an oversight.
Case1: pfn < start_pfn
<at memory compaction for node Y>
| node X's zone | node Y's zone
+-----------------+------------------------------...
pageblock ^ ^ ^
+-----------+-----------+-----------+-----------+...
^ ^ ^
^ ^ end_pfn
^ start_pfn = cc->zone->zone_start_pfn
pfn
<---------> scanned range by "Scan After"
Case2: end_pfn < pfn
<at memory compaction for node X>
| node X's zone | node Y's zone
+-----------------+------------------------------...
pageblock ^ ^ ^
+-----------+-----------+-----------+-----------+...
^ ^ ^
^ ^ pfn
^ end_pfn
start_pfn
<---------> scanned range by "Scan Before"
It seems that there is no good reason to skip nr_isolated pages just after
given pfn. So let perform simple scan from start to end instead of
dividing the scan into "Before" and "After".
Link: https://lkml.kernel.org/r/20221026112438.236336-1-a.naribayashi@fujitsu.com
Fixes: 6e2b7044c1 ("mm, compaction: make fast_isolate_freepages() stay within zone").
Signed-off-by: NARIBAYASHI Akira <a.naribayashi@fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This documents the new /sys/class/bdi/<bdi>/max_ratio_fine knob.
[akpm@linux-foundation.org: fix htmldocs warnings]
Link: https://lkml.kernel.org/r/20221119005215.3052436-21-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This adds the min_ratio_fine knob. The knob specifies the values not
based on 1 of 100, but instead 1 per million.
Link: https://lkml.kernel.org/r/20221119005215.3052436-20-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This introduces bdi_set_min_ratio_no_scale(). It uses the max
granularity for the ratio. This function by the new sysfs knob
min_ratio_fine.
Link: https://lkml.kernel.org/r/20221119005215.3052436-19-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This documents the new /sys/class/bdi/<bdi>/max_ratio_fine knob.
[akpm@linux-foundation.org: fix htmldocs warnings]
Link: https://lkml.kernel.org/r/20221119005215.3052436-18-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This adds the max_ratio_fine knob. The knob specifies the values not
based on 1 of 100, but instead 1 per million.
Link: https://lkml.kernel.org/r/20221119005215.3052436-17-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This introduces bdi_set_max_ratio_no_scale(). It uses the max
granularity for the ratio. This function by the new sysfs knob
max_ratio_fine.
Link: https://lkml.kernel.org/r/20221119005215.3052436-16-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This documents the new /sys/class/bdi/<bdi>/min_bytes knob.
[akpm@linux-foundation.org: fix htmldocs warnings]
Link: https://lkml.kernel.org/r/20221119005215.3052436-15-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
bdi has two existing knobs to limit the amount of dirty memory:
min_ratio and max_ratio. However the granularity of the knobs is limited
and often it is more convenient to specify limits in terms of bytes.
This change adds the min_bytes knob.
It does not store the min_bytes value, instead it converts the max_bytes
value to a ratio. The value is therefore more an approximation than an
absolute value.
It also maintains the sum over all the bdi min_ratio values stored in
the variable bdi_min_ratio.
Link: https://lkml.kernel.org/r/20221119005215.3052436-14-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This introduces the bdi_set_min_bytes() function. The min_bytes function
does not store the min_bytes value. Instead it converts the min_bytes
value into the corresponding ratio value.
Link: https://lkml.kernel.org/r/20221119005215.3052436-13-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This splits off the __bdi_set_min_ratio() function from the
bdi_set_min_ratio() function. The __bdi_set_min_ratio() function will
also be called from the bdi_set_min_bytes() function, which will be
introduced in the next patch.
Link: https://lkml.kernel.org/r/20221119005215.3052436-12-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This adds a function to return the specified value for min_bytes. It
converts the stored min_ratio of the bdi to the corresponding bytes
value. This is an approximation as it is based on the value that is
returned by global_dirty_limits(), which can change. The returned
value can be different than the value when the min_bytes value was set.
Link: https://lkml.kernel.org/r/20221119005215.3052436-11-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This documents the new /sys/class/bdi/<bdi>/max_bytes knob.
Link: https://lkml.kernel.org/r/20221119005215.3052436-10-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This adds the new knob max_bytes to specify a dirty memory limit for the
corresponding bdi. The specified bytes value is converted to a ratio.
Link: https://lkml.kernel.org/r/20221119005215.3052436-9-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This introduces the bdi_set_max_bytes() function. The max_bytes function
does not store the max_bytes value. Instead it converts the max_bytes
value into the corresponding ratio value.
Link: https://lkml.kernel.org/r/20221119005215.3052436-8-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This splits off __bdi_set_max_ratio() from bdi_set_max_ratio().
__bdi_set_max_ratio() will also be called from bdi_set_max_bytes(),
which will be introduced in the next patch.
Link: https://lkml.kernel.org/r/20221119005215.3052436-7-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This adds a function to return the specified value for max_bytes. It
converts the stored max_ratio of the bdi to the corresponding bytes
value. It introduces the bdi_get_bytes helper function to do the
conversion. This is an approximation as it is based on the value that is
returned by global_dirty_limits(), which can change. The helper function
will also be used by the min_bytes bdi knob.
Link: https://lkml.kernel.org/r/20221119005215.3052436-6-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
To get finer granularity for ratio calculations use part per million
instead of percentiles. This is especially important if we want to
automatically convert byte values to ratios. Otherwise the values that
are actually used can be quite different. This is also important for
machines with more main memory (1% of 256GB is already 2.5GB).
Link: https://lkml.kernel.org/r/20221119005215.3052436-5-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This documents the new /sys/class/bdi/<bdi>/strict_limit knob.
Link: https://lkml.kernel.org/r/20221119005215.3052436-4-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add a new knob to /sys/class/bdi/<bdi>/strict_limit. This new knob
allows to set/unset the flag BDI_CAP_STRICTLIMIT in the bdi
capabilities.
Link: https://lkml.kernel.org/r/20221119005215.3052436-3-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Chris Mason <clm@meta.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/block: add bdi sysfs knobs", v4.
At meta network block devices (nbd) are used to implement remote block
storage. In testing and during production it has been observed that these
network block devices can consume a huge portion of the dirty writeback
cache and writeback can take a considerable time.
To be able to give stricter limits, I'm proposing the following changes:
1) introduce strictlimit knob
Currently the max_ratio knob exists to limit the dirty_memory. However
this knob only applies once (dirty_ratio + dirty_background_ratio) / 2
has been reached.
With the BDI_CAP_STRICTLIMIT flag, the max_ratio can be applied without
reaching that limit. This change exposes that knob.
This knob can also be useful for NFS, fuse filesystems and USB devices.
2) Use part of 1000000 internal calculation
The max_ratio is based on percentage. With the current machine sizes
percentage values can be very high (1% of a 256GB main memory is already
2.5GB). This change uses part of 1000000 instead of percentages for the
internal calculations.
3) Introduce two new sysfs knobs: min_bytes and max_bytes.
Currently all calculations are based on ratio, but for a user it often
more convenient to specify a limit in bytes. The new knobs will not
store bytes values, instead they will translate the byte value to a
corresponding ratio. As the internal values are now part of 1000, the
ratio is closer to the specified value. However the value should be more
seen as an approximation as it can fluctuate over time.
3) Introduce two new sysfs knobs: min_ratio_fine and max_ratio_fine.
The granularity for the existing sysfs bdi knobs min_ratio and max_ratio
is based on percentage values. The new sysfs bdi knobs min_ratio_fine
and max_ratio_fine allow to specify the ratio as part of 1 million.
This patch (of 20):
This adds the bdi_set_strict_limit function to be able to set/unset the
BDI_CAP_STRICTLIMIT flag.
Link: https://lkml.kernel.org/r/20221119005215.3052436-1-shr@devkernel.io
Link: https://lkml.kernel.org/r/20221119005215.3052436-2-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Chris Mason <clm@meta.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Prevent a kconfig warning that is caused by TEST_MAPLE_TREE by adding a
"depends on" clause for TEST_MAPLE_TREE since 'select' does not follow any
kconfig dependencies.
WARNING: unmet direct dependencies detected for DEBUG_MAPLE_TREE
Depends on [n]: DEBUG_KERNEL [=n]
Selected by [y]:
- TEST_MAPLE_TREE [=y] && RUNTIME_TESTING_MENU [=y]
Link: https://lkml.kernel.org/r/20221119055117.14094-1-rdunlap@infradead.org
Fixes: 120b116208 ("maple_tree: reorganize testing to restore module testing")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There are no more callers of try_to_release_page(), so remove it. This
saves 85 bytes of kernel text.
Link: https://lkml.kernel.org/r/20221118073055.55694-5-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Replace try_to_release_page() with filemap_release_folio(). This change
is in preparation for the removal of the try_to_release_page() wrapper.
Link: https://lkml.kernel.org/r/20221118073055.55694-4-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Replace some calls with their folio equivalents. This change removes 4
calls to compound_head() and is in preparation for the removal of the
try_to_release_page() wrapper.
Link: https://lkml.kernel.org/r/20221118073055.55694-3-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Removing the try_to_release_page() wrapper", v3.
This patchset replaces the remaining calls of try_to_release_page() with
the folio equivalent: filemap_release_folio(). This allows us to remove
the wrapper.
This patch (of 4):
Convert move_extent_per_page() to use folios. This change removes 5 calls
to compound_head() and is in preparation for the removal of the
try_to_release_page() wrapper.
Link: https://lkml.kernel.org/r/20221118073055.55694-1-vishal.moola@gmail.com
Link: https://lkml.kernel.org/r/20221118073055.55694-2-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
While freeing a large list, the zone lock will be released and reacquired
to avoid long hold times since commit c24ad77d96 ("mm/page_alloc.c:
avoid excessive IRQ disabled times in free_unref_page_list()"). As
suggested by Vlastimil Babka, the lockrelease/reacquire logic can be
simplified by reusing the logic that acquires a different lock when
changing zones.
Link: https://lkml.kernel.org/r/20221122131229.5263-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The pcp_spin_lock_irqsave protecting the PCP lists is IRQ-safe as a task
allocating from the PCP must not re-enter the allocator from IRQ context.
In each instance where IRQ-reentrancy is possible, the lock is acquired
using pcp_spin_trylock_irqsave() even though IRQs are disabled and
re-entrancy is impossible.
Demote the lock to pcp_spin_lock avoids an IRQ disable/enable in the
common case at the cost of some IRQ allocations taking a slower path. If
the PCP lists need to be refilled, the zone lock still needs to disable
IRQs but that will only happen on PCP refill and drain. If an IRQ is
raised when a PCP allocation is in progress, the trylock will fail and
fallback to using the buddy lists directly. Note that this may not be a
universal win if an interrupt-intensive workload also allocates heavily
from interrupt context and contends heavily on the zone->lock as a result.
[mgorman@techsingularity.net: migratetype might be wrong if a PCP was locked]
Link: https://lkml.kernel.org/r/20221122131229.5263-2-mgorman@techsingularity.net
[yuzhao@google.com: reported lockdep issue on IO completion from softirq]
[hughd@google.com: fix list corruption, lock improvements, micro-optimsations]
Link: https://lkml.kernel.org/r/20221118101714.19590-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Leave IRQs enabled for per-cpu page allocations", v3.
This patch (of 2):
free_unref_page_list() has neglected to remove pages properly from the
list of pages to free since forever. It works by coincidence because
list_add happened to do the right thing adding the pages to just the PCP
lists. However, a later patch added pages to either the PCP list or the
zone list but only properly deleted the page from the list in one path
leading to list corruption and a subsequent failure. As a preparation
patch, always delete the pages from one list properly before adding to
another. On its own, this fixes nothing although it adds a fractional
amount of overhead but is critical to the next patch.
Link: https://lkml.kernel.org/r/20221118101714.19590-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20221118101714.19590-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
