linux.git/mm/internal.h, branch v6.14

mm: memory-failure: update ttu flag inside unmap_poisoned_folio

2025-03-06T05:36:13+00:00

Patch series "mm: memory_failure: unmap poisoned folio during migrate
properly", v3.

Fix two bugs during folio migration if the folio is poisoned.


This patch (of 3):

Commit 6da6b1d4a7df ("mm/hwpoison: convert TTU_IGNORE_HWPOISON to
TTU_HWPOISON") introduce TTU_HWPOISON to replace TTU_IGNORE_HWPOISON in
order to stop send SIGBUS signal when accessing an error page after a
memory error on a clean folio.  However during page migration, anon folio
must be set with TTU_HWPOISON during unmap_*().  For pagecache we need
some policy just like the one in hwpoison_user_mappings to set this flag. 
So move this policy from hwpoison_user_mappings to unmap_poisoned_folio to
handle this warning properly.

Warning will be produced during unamp poison folio with the following log:

  ------------[ cut here ]------------
  WARNING: CPU: 1 PID: 365 at mm/rmap.c:1847 try_to_unmap_one+0x8fc/0xd3c
  Modules linked in:
  CPU: 1 UID: 0 PID: 365 Comm: bash Tainted: G        W          6.13.0-rc1-00018-gacdb4bbda7ab #42
  Tainted: [W]=WARN
  Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
  pstate: 20400005 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  pc : try_to_unmap_one+0x8fc/0xd3c
  lr : try_to_unmap_one+0x3dc/0xd3c
  Call trace:
   try_to_unmap_one+0x8fc/0xd3c (P)
   try_to_unmap_one+0x3dc/0xd3c (L)
   rmap_walk_anon+0xdc/0x1f8
   rmap_walk+0x3c/0x58
   try_to_unmap+0x88/0x90
   unmap_poisoned_folio+0x30/0xa8
   do_migrate_range+0x4a0/0x568
   offline_pages+0x5a4/0x670
   memory_block_action+0x17c/0x374
   memory_subsys_offline+0x3c/0x78
   device_offline+0xa4/0xd0
   state_store+0x8c/0xf0
   dev_attr_store+0x18/0x2c
   sysfs_kf_write+0x44/0x54
   kernfs_fop_write_iter+0x118/0x1a8
   vfs_write+0x3a8/0x4bc
   ksys_write+0x6c/0xf8
   __arm64_sys_write+0x1c/0x28
   invoke_syscall+0x44/0x100
   el0_svc_common.constprop.0+0x40/0xe0
   do_el0_svc+0x1c/0x28
   el0_svc+0x30/0xd0
   el0t_64_sync_handler+0xc8/0xcc
   el0t_64_sync+0x198/0x19c
  ---[ end trace 0000000000000000 ]---

[mawupeng1@huawei.com: unmap_poisoned_folio(): remove shadowed local `mapping', per Miaohe]
  Link: https://lkml.kernel.org/r/20250219060653.3849083-1-mawupeng1@huawei.com
Link: https://lkml.kernel.org/r/20250217014329.3610326-1-mawupeng1@huawei.com
Link: https://lkml.kernel.org/r/20250217014329.3610326-2-mawupeng1@huawei.com
Fixes: 6da6b1d4a7df ("mm/hwpoison: convert TTU_IGNORE_HWPOISON to TTU_HWPOISON")
Signed-off-by: Ma Wupeng 
Suggested-by: David Hildenbrand 
Acked-by: David Hildenbrand 
Acked-by: Miaohe Lin 
Cc: Ma Wupeng 
Cc: Michal Hocko 
Cc: Naoya Horiguchi 
Cc: Oscar Salvador 
Cc: 
Signed-off-by: Andrew Morton

mm/truncate: add folio_unmap_invalidate() helper

2025-01-26T04:22:43+00:00

Add a folio_unmap_invalidate() helper, which unmaps and invalidates a
given folio.  The caller must already have locked the folio.  Embed the
old invalidate_complete_folio2() helper in there as well, as nobody else
calls it.

Use this new helper in invalidate_inode_pages2_range(), rather than
duplicate the code there.

In preparation for using this elsewhere as well, have it take a gfp_t mask
rather than assume GFP_KERNEL is the right choice.  This bubbles back to
invalidate_complete_folio2() as well.

Link: https://lkml.kernel.org/r/20241220154831.1086649-7-axboe@kernel.dk
Signed-off-by: Jens Axboe 
Cc: Brian Foster 
Cc: Chris Mason 
Cc: Christoph Hellwig 
Cc: Johannes Weiner 
Cc: Kirill A. Shutemov 
Cc: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton

mseal: remove can_do_mseal()

2025-01-14T06:40:51+00:00

No code logic change.

can_do_mseal() is called exclusively by mseal.c, and mseal.c is compiled
only when CONFIG_64BIT flag is set in makefile.  Therefore, it is
unnecessary to have 32 bit stub function in the header file, remove this
function and merge the logic into do_mseal().

Link: https://lkml.kernel.org/r/20241206013934.2782793-1-jeffxu@google.com
Link: https://lkml.kernel.org/r/20241206194839.3030596-2-jeffxu@google.com
Signed-off-by: Jeff Xu 
Reviewed-by: Lorenzo Stoakes 
Cc: Jorge Lucangeli Obes 
Cc: Kees Cook 
Cc: Liam R. Howlett 
Cc: Pedro Falcato 
Cc: Randy Dunlap 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

mm: pgtable: reclaim empty PTE page in madvise(MADV_DONTNEED)

2025-01-14T06:40:48+00:00

Now in order to pursue high performance, applications mostly use some
high-performance user-mode memory allocators, such as jemalloc or
tcmalloc.  These memory allocators use madvise(MADV_DONTNEED or MADV_FREE)
to release physical memory, but neither MADV_DONTNEED nor MADV_FREE will
release page table memory, which may cause huge page table memory usage.

The following are a memory usage snapshot of one process which actually
happened on our server:

        VIRT:  55t
        RES:   590g
        VmPTE: 110g

In this case, most of the page table entries are empty.  For such a PTE
page where all entries are empty, we can actually free it back to the
system for others to use.

As a first step, this commit aims to synchronously free the empty PTE
pages in madvise(MADV_DONTNEED) case.  We will detect and free empty PTE
pages in zap_pte_range(), and will add zap_details.reclaim_pt to exclude
cases other than madvise(MADV_DONTNEED).

Once an empty PTE is detected, we first try to hold the pmd lock within
the pte lock.  If successful, we clear the pmd entry directly (fast path).
Otherwise, we wait until the pte lock is released, then re-hold the pmd
and pte locks and loop PTRS_PER_PTE times to check pte_none() to re-detect
whether the PTE page is empty and free it (slow path).

For other cases such as madvise(MADV_FREE), consider scanning and freeing
empty PTE pages asynchronously in the future.

The following code snippet can show the effect of optimization:

        mmap 50G
        while (1) {
                for (; i < 1024 * 25; i++) {
                        touch 2M memory
                        madvise MADV_DONTNEED 2M
                }
        }

As we can see, the memory usage of VmPTE is reduced:

                        before                          after
VIRT                   50.0 GB                        50.0 GB
RES                     3.1 MB                         3.1 MB
VmPTE                102640 KB                         240 KB

[zhengqi.arch@bytedance.com: fix uninitialized symbol 'ptl']
  Link: https://lkml.kernel.org/r/20241206112348.51570-1-zhengqi.arch@bytedance.com
  Link: https://lore.kernel.org/linux-mm/224e6a4e-43b5-4080-bdd8-b0a6fb2f0853@stanley.mountain/
Link: https://lkml.kernel.org/r/92aba2b319a734913f18ba41e7d86a265f0b84e2.1733305182.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng 
Cc: Andy Lutomirski 
Cc: Catalin Marinas 
Cc: Dave Hansen 
Cc: David Hildenbrand 
Cc: David Rientjes 
Cc: Hugh Dickins 
Cc: Jann Horn 
Cc: Lorenzo Stoakes 
Cc: Matthew Wilcox 
Cc: Mel Gorman 
Cc: Muchun Song 
Cc: Peter Xu 
Cc: Peter Zijlstra 
Cc: Will Deacon 
Cc: Zach O'Keefe 
Cc: Dan Carpenter 
Signed-off-by: Andrew Morton

mm/page_alloc: make __alloc_contig_migrate_range() static

2025-01-14T06:40:44+00:00

The single user is in page_alloc.c.

Link: https://lkml.kernel.org/r/20241203094732.200195-4-david@redhat.com
Signed-off-by: David Hildenbrand 
Reviewed-by: Zi Yan 
Reviewed-by: Vlastimil Babka 
Reviewed-by: Oscar Salvador 
Reviewed-by: Vishal Moola (Oracle) 
Cc: Christophe Leroy 
Cc: Madhavan Srinivasan 
Cc: Michael Ellerman 
Cc: Naveen N Rao 
Cc: Nicholas Piggin 
Signed-off-by: Andrew Morton

mm/mempolicy: add alloc_frozen_pages()

2025-01-14T06:40:33+00:00

Provide an interface to allocate pages from the page allocator without
incrementing their refcount.  This saves an atomic operation on free,
which may be beneficial to some users (eg slab).

Link: https://lkml.kernel.org/r/20241125210149.2976098-15-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: William Kucharski 
Reviewed-by: Vlastimil Babka 
Cc: David Hildenbrand 
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Mel Gorman 
Cc: Miaohe Lin 
Cc: Muchun Song 
Signed-off-by: Andrew Morton

mm/page_alloc: add __alloc_frozen_pages()

2025-01-14T06:40:33+00:00

Defer the initialisation of the page refcount to the new __alloc_pages()
wrapper and turn the old __alloc_pages() into __alloc_frozen_pages().

Link: https://lkml.kernel.org/r/20241125210149.2976098-14-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Zi Yan 
Acked-by: David Hildenbrand 
Reviewed-by: Vlastimil Babka 
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Mel Gorman 
Cc: Miaohe Lin 
Cc: Muchun Song 
Cc: William Kucharski 
Signed-off-by: Andrew Morton

mm/page_alloc: move set_page_refcounted() to callers of post_alloc_hook()

2025-01-14T06:40:31+00:00

In preparation for allocating frozen pages, stop initialising the page
refcount in post_alloc_hook().

Link: https://lkml.kernel.org/r/20241125210149.2976098-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Miaohe Lin 
Reviewed-by: Zi Yan 
Acked-by: David Hildenbrand 
Reviewed-by: Vlastimil Babka 
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Mel Gorman 
Cc: Muchun Song 
Cc: William Kucharski 
Signed-off-by: Andrew Morton

mm/page_alloc: export free_frozen_pages() instead of free_unref_page()

2025-01-14T06:40:31+00:00

We already have the concept of "frozen pages" (eg page_ref_freeze()), so
let's not complicate things by also having the concept of "unref pages".

Link: https://lkml.kernel.org/r/20241125210149.2976098-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: David Hildenbrand 
Reviewed-by: William Kucharski 
Reviewed-by: Miaohe Lin 
Reviewed-by: Muchun Song 
Reviewed-by: Zi Yan 
Reviewed-by: Vlastimil Babka 
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Mel Gorman 
Signed-off-by: Andrew Morton

mm, madvise: fix potential workingset node list_lru leaks

2024-12-31T01:59:11+00:00

Since commit 5abc1e37afa0 ("mm: list_lru: allocate list_lru_one only when
needed"), all list_lru users need to allocate the items using the new
infrastructure that provides list_lru info for slab allocation, ensuring
that the corresponding memcg list_lru is allocated before use.

For workingset shadow nodes (which are xa_node), users are converted to
use the new infrastructure by commit 9bbdc0f32409 ("xarray: use
kmem_cache_alloc_lru to allocate xa_node").  The xas->xa_lru will be set
correctly for filemap users.  However, there is a missing case: xa_node
allocations caused by madvise(..., MADV_COLLAPSE).

madvise(..., MADV_COLLAPSE) will also read in the absent parts of file
map, and there will be xa_nodes allocated for the caller's memcg (assuming
it's not rootcg).  However, these allocations won't trigger memcg list_lru
allocation because the proper xas info was not set.

If nothing else has allocated other xa_nodes for that memcg to trigger
list_lru creation, and memory pressure starts to evict file pages,
workingset_update_node will try to add these xa_nodes to their
corresponding memcg list_lru, and it does not exist (NULL).  So they will
be added to rootcg's list_lru instead.

This shouldn't be a significant issue in practice, but it is indeed
unexpected behavior, and these xa_nodes will not be reclaimed effectively.
And may lead to incorrect counting of the list_lru->nr_items counter.

This problem wasn't exposed until recent commit 28e98022b31ef
("mm/list_lru: simplify reparenting and initial allocation") added a
sanity check: only dying memcg could have a NULL list_lru when
list_lru_{add,del} is called.  This problem triggered this WARNING.

So make madvise(..., MADV_COLLAPSE) also call xas_set_lru() to pass the
list_lru which we may want to insert xa_node into later.  And move
mapping_set_update to mm/internal.h, and turn into a macro to avoid
including extra headers in mm/internal.h.

Link: https://lkml.kernel.org/r/20241222122936.67501-1-ryncsn@gmail.com
Fixes: 9bbdc0f32409 ("xarray: use kmem_cache_alloc_lru to allocate xa_node")
Reported-by: syzbot+38a0cbd267eff2d286ff@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/lkml/675d01e9.050a0220.37aaf.00be.GAE@google.com/
Signed-off-by: Kairui Song 
Cc: Chengming Zhou 
Cc: Johannes Weiner 
Cc: Matthew Wilcox (Oracle) 
Cc: Michal Hocko 
Cc: Muchun Song 
Cc: Qi Zheng 
Cc: Roman Gushchin 
Cc: Sasha Levin 
Cc: Shakeel Butt 
Cc: Yu Zhao 
Signed-off-by: Andrew Morton