The commit 2c653d0e ("ksm: introduce ksm_max_page_sharing per page
deduplication limit") introduced a possible failure case in the
stable_tree_insert(), where we may free the new allocated stable_node_dup
if we fail to prepare the missing chain node.

Then that kfolio return and unlock with a freed stable_node set...  And
any MM activities can come in to access kfolio->mapping, so UAF.

Fix it by moving folio_set_stable_node() to the end after stable_node
is inserted successfully.

Link: https://lkml.kernel.org/r/20240513-b4-ksm-stable-node-uaf-v1-1-f687de76f452@linux.dev


Fixes: 2c653d0e ("ksm: introduce ksm_max_page_sharing per page deduplication limit")
Signed-off-by: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Stefan Roesch <shr@devkernel.io>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

When I did memory failure tests recently, below panic occurs:

page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8cee00
flags: 0x6fffe0000000000(node=1|zone=2|lastcpupid=0x7fff)
raw: 06fffe0000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000009 00000000ffffffff 0000000000000000
page dumped because: VM_BUG_ON_PAGE(!PageBuddy(page))
------------[ cut here ]------------
kernel BUG at include/linux/page-flags.h:1009!
invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
RIP: 0010:__del_page_from_free_list+0x151/0x180
RSP: 0018:ffffa49c90437998 EFLAGS: 00000046
RAX: 0000000000000035 RBX: 0000000000000009 RCX: ffff8dd8dfd1c9c8
RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff8dd8dfd1c9c0
RBP: ffffd901233b8000 R08: ffffffffab5511f8 R09: 0000000000008c69
R10: 0000000000003c15 R11: ffffffffab5511f8 R12: ffff8dd8fffc0c80
R13: 0000000000000001 R14: ffff8dd8fffc0c80 R15: 0000000000000009
FS:  00007ff916304740(0000) GS:ffff8dd8dfd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055eae50124c8 CR3: 00000008479e0000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __rmqueue_pcplist+0x23b/0x520
 get_page_from_freelist+0x26b/0xe40
 __alloc_pages_noprof+0x113/0x1120
 __folio_alloc_noprof+0x11/0xb0
 alloc_buddy_hugetlb_folio.isra.0+0x5a/0x130
 __alloc_fresh_hugetlb_folio+0xe7/0x140
 alloc_pool_huge_folio+0x68/0x100
 set_max_huge_pages+0x13d/0x340
 hugetlb_sysctl_handler_common+0xe8/0x110
 proc_sys_call_handler+0x194/0x280
 vfs_write+0x387/0x550
 ksys_write+0x64/0xe0
 do_syscall_64+0xc2/0x1d0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff916114887
RSP: 002b:00007ffec8a2fd78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000055eae500e350 RCX: 00007ff916114887
RDX: 0000000000000004 RSI: 000055eae500e390 RDI: 0000000000000003
RBP: 000055eae50104c0 R08: 0000000000000000 R09: 000055eae50104c0
R10: 0000000000000077 R11: 0000000000000246 R12: 0000000000000004
R13: 0000000000000004 R14: 00007ff916216b80 R15: 00007ff916216a00
 </TASK>
Modules linked in: mce_inject hwpoison_inject
---[ end trace 0000000000000000 ]---

And before the panic, there had an warning about bad page state:

BUG: Bad page state in process page-types  pfn:8cee00
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8cee00
flags: 0x6fffe0000000000(node=1|zone=2|lastcpupid=0x7fff)
page_type: 0xffffff7f(buddy)
raw: 06fffe0000000000 ffffd901241c0008 ffffd901240f8008 0000000000000000
raw: 0000000000000000 0000000000000009 00000000ffffff7f 0000000000000000
page dumped because: nonzero mapcount
Modules linked in: mce_inject hwpoison_inject
CPU: 8 PID: 154211 Comm: page-types Not tainted 6.9.0-rc4-00499-g5544ec3178e2-dirty #22
Call Trace:
 <TASK>
 dump_stack_lvl+0x83/0xa0
 bad_page+0x63/0xf0
 free_unref_page+0x36e/0x5c0
 unpoison_memory+0x50b/0x630
 simple_attr_write_xsigned.constprop.0.isra.0+0xb3/0x110
 debugfs_attr_write+0x42/0x60
 full_proxy_write+0x5b/0x80
 vfs_write+0xcd/0x550
 ksys_write+0x64/0xe0
 do_syscall_64+0xc2/0x1d0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f189a514887
RSP: 002b:00007ffdcd899718 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f189a514887
RDX: 0000000000000009 RSI: 00007ffdcd899730 RDI: 0000000000000003
RBP: 00007ffdcd8997a0 R08: 0000000000000000 R09: 00007ffdcd8994b2
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdcda199a8
R13: 0000000000404af1 R14: 000000000040ad78 R15: 00007f189a7a5040
 </TASK>

The root cause should be the below race:

 memory_failure
  try_memory_failure_hugetlb
   me_huge_page
    __page_handle_poison
     dissolve_free_hugetlb_folio
     drain_all_pages -- Buddy page can be isolated e.g. for compaction.
     take_page_off_buddy -- Failed as page is not in the buddy list.
	     -- Page can be putback into buddy after compaction.
    page_ref_inc -- Leads to buddy page with refcnt = 1.

Then unpoison_memory() can unpoison the page and send the buddy page back
into buddy list again leading to the above bad page state warning.  And
bad_page() will call page_mapcount_reset() to remove PageBuddy from buddy
page leading to later VM_BUG_ON_PAGE(!PageBuddy(page)) when trying to
allocate this page.

Fix this issue by only treating __page_handle_poison() as successful when
it returns 1.

Link: https://lkml.kernel.org/r/20240523071217.1696196-1-linmiaohe@huawei.com


Fixes: ceaf8fbe ("mm, hwpoison: skip raw hwpoison page in freeing 1GB hugepage")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

When I did memory failure tests recently, below panic occurs:

 kernel BUG at include/linux/mm.h:1135!
 invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
 CPU: 9 PID: 137 Comm: kswapd1 Not tainted 6.9.0-rc4-00491-gd5ce28f156fe-dirty #14
 RIP: 0010:shrink_huge_zero_page_scan+0x168/0x1a0
 RSP: 0018:ffff9933c6c57bd0 EFLAGS: 00000246
 RAX: 000000000000003e RBX: 0000000000000000 RCX: ffff88f61fc5c9c8
 RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff88f61fc5c9c0
 RBP: ffffcd7c446b0000 R08: ffffffff9a9405f0 R09: 0000000000005492
 R10: 00000000000030ea R11: ffffffff9a9405f0 R12: 0000000000000000
 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88e703c4ac00
 FS:  0000000000000000(0000) GS:ffff88f61fc40000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000055f4da6e9878 CR3: 0000000c71048000 CR4: 00000000000006f0
 Call Trace:
  <TASK>
  do_shrink_slab+0x14f/0x6a0
  shrink_slab+0xca/0x8c0
  shrink_node+0x2d0/0x7d0
  balance_pgdat+0x33a/0x720
  kswapd+0x1f3/0x410
  kthread+0xd5/0x100
  ret_from_fork+0x2f/0x50
  ret_from_fork_asm+0x1a/0x30
  </TASK>
 Modules linked in: mce_inject hwpoison_inject
 ---[ end trace 0000000000000000 ]---
 RIP: 0010:shrink_huge_zero_page_scan+0x168/0x1a0
 RSP: 0018:ffff9933c6c57bd0 EFLAGS: 00000246
 RAX: 000000000000003e RBX: 0000000000000000 RCX: ffff88f61fc5c9c8
 RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff88f61fc5c9c0
 RBP: ffffcd7c446b0000 R08: ffffffff9a9405f0 R09: 0000000000005492
 R10: 00000000000030ea R11: ffffffff9a9405f0 R12: 0000000000000000
 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88e703c4ac00
 FS:  0000000000000000(0000) GS:ffff88f61fc40000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000055f4da6e9878 CR3: 0000000c71048000 CR4: 00000000000006f0

The root cause is that HWPoison flag will be set for huge_zero_folio
without increasing the folio refcnt.  But then unpoison_memory() will
decrease the folio refcnt unexpectedly as it appears like a successfully
hwpoisoned folio leading to VM_BUG_ON_PAGE(page_ref_count(page) == 0) when
releasing huge_zero_folio.

Skip unpoisoning huge_zero_folio in unpoison_memory() to fix this issue. 
We're not prepared to unpoison huge_zero_folio yet.

Link: https://lkml.kernel.org/r/20240516122608.22610-1-linmiaohe@huawei.com


Fixes: 478d134e ("mm/huge_memory: do not overkill when splitting huge_zero_page")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Xu Yu <xuyu@linux.alibaba.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

commit a421ef30 ("mm: allow !GFP_KERNEL allocations for kvmalloc")
includes support for __GFP_NOFAIL, but it presents a conflict with commit
dd544141 ("vmalloc: back off when the current task is OOM-killed").  A
possible scenario is as follows:

process-a
__vmalloc_node_range(GFP_KERNEL | __GFP_NOFAIL)
    __vmalloc_area_node()
        vm_area_alloc_pages()
		--> oom-killer send SIGKILL to process-a
        if (fatal_signal_pending(current)) break;
--> return NULL;

To fix this, do not check fatal_signal_pending() in vm_area_alloc_pages()
if __GFP_NOFAIL set.

This issue occurred during OPLUS KASAN TEST. Below is part of the log
-> oom-killer sends signal to process
[65731.222840] [ T1308] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/apps/uid_10198,task=gs.intelligence,pid=32454,uid=10198

[65731.259685] [T32454] Call trace:
[65731.259698] [T32454]  dump_backtrace+0xf4/0x118
[65731.259734] [T32454]  show_stack+0x18/0x24
[65731.259756] [T32454]  dump_stack_lvl+0x60/0x7c
[65731.259781] [T32454]  dump_stack+0x18/0x38
[65731.259800] [T32454]  mrdump_common_die+0x250/0x39c [mrdump]
[65731.259936] [T32454]  ipanic_die+0x20/0x34 [mrdump]
[65731.260019] [T32454]  atomic_notifier_call_chain+0xb4/0xfc
[65731.260047] [T32454]  notify_die+0x114/0x198
[65731.260073] [T32454]  die+0xf4/0x5b4
[65731.260098] [T32454]  die_kernel_fault+0x80/0x98
[65731.260124] [T32454]  __do_kernel_fault+0x160/0x2a8
[65731.260146] [T32454]  do_bad_area+0x68/0x148
[65731.260174] [T32454]  do_mem_abort+0x151c/0x1b34
[65731.260204] [T32454]  el1_abort+0x3c/0x5c
[65731.260227] [T32454]  el1h_64_sync_handler+0x54/0x90
[65731.260248] [T32454]  el1h_64_sync+0x68/0x6c

[65731.260269] [T32454]  z_erofs_decompress_queue+0x7f0/0x2258
--> be->decompressed_pages = kvcalloc(be->nr_pages, sizeof(struct page *), GFP_KERNEL | __GFP_NOFAIL);
	kernel panic by NULL pointer dereference.
	erofs assume kvmalloc with __GFP_NOFAIL never return NULL.
[65731.260293] [T32454]  z_erofs_runqueue+0xf30/0x104c
[65731.260314] [T32454]  z_erofs_readahead+0x4f0/0x968
[65731.260339] [T32454]  read_pages+0x170/0xadc
[65731.260364] [T32454]  page_cache_ra_unbounded+0x874/0xf30
[65731.260388] [T32454]  page_cache_ra_order+0x24c/0x714
[65731.260411] [T32454]  filemap_fault+0xbf0/0x1a74
[65731.260437] [T32454]  __do_fault+0xd0/0x33c
[65731.260462] [T32454]  handle_mm_fault+0xf74/0x3fe0
[65731.260486] [T32454]  do_mem_abort+0x54c/0x1b34
[65731.260509] [T32454]  el0_da+0x44/0x94
[65731.260531] [T32454]  el0t_64_sync_handler+0x98/0xb4
[65731.260553] [T32454]  el0t_64_sync+0x198/0x19c

Link: https://lkml.kernel.org/r/20240510100131.1865-1-hailong.liu@oppo.com


Fixes: 9376130c ("mm/vmalloc: add support for __GFP_NOFAIL")
Signed-off-by: Hailong.Liu <hailong.liu@oppo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Barry Song <21cnbao@gmail.com>
Reported-by: Oven <liyangouwen1@oppo.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Gao Xiang <xiang@kernel.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

The new mseal() is an syscall on 64 bit CPU, and with following signature:

int mseal(void addr, size_t len, unsigned long flags)
addr/len: memory range.
flags: reserved.

mseal() blocks following operations for the given memory range.

1> Unmapping, moving to another location, and shrinking the size,
   via munmap() and mremap(), can leave an empty space, therefore can
   be replaced with a VMA with a new set of attributes.

2> Moving or expanding a different VMA into the current location,
   via mremap().

3> Modifying a VMA via mmap(MAP_FIXED).

4> Size expansion, via mremap(), does not appear to pose any specific
   risks to sealed VMAs. It is included anyway because the use case is
   unclear. In any case, users can rely on merging to expand a sealed VMA.

5> mprotect() and pkey_mprotect().

6> Some destructive madvice() behaviors (e.g. MADV_DONTNEED) for anonymous
   memory, when users don't have write permission to the memory. Those
   behaviors can alter region contents by discarding pages, effectively a
   memset(0) for anonymous memory.

Following input during RFC are incooperated into this patch:

Jann Horn: raising awareness and providing valuable insights on the
destructive madvise operations.
Linus Torvalds: assisting in defining system call signature and scope.
Liam R. Howlett: perf optimization.
Theo de Raadt: sharing the experiences and insight gained from
  implementing mimmutable() in OpenBSD.

Finally, the idea that inspired this patch comes from Stephen Röttger's
work in Chrome V8 CFI.

[jeffxu@chromium.org: add branch prediction hint, per Pedro]
  Link: https://lkml.kernel.org/r/20240423192825.1273679-2-jeffxu@chromium.org
Link: https://lkml.kernel.org/r/20240415163527.626541-3-jeffxu@chromium.org


Signed-off-by: Jeff Xu <jeffxu@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Jann Horn <jannh@google.com>
Cc: Jeff Xu <jeffxu@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Cc: Stephen Röttger <sroettger@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Amer Al Shanawany <amer.shanawany@gmail.com>
Cc: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Use '%pD' to print out the filename, and print out the actual offset
within the file too, rather than just what the virtual address of the
mapping is (which doesn't tell you anything about any mapping offsets).

Also, use the exact vma_lookup() instead of find_vma() - the latter
looks up any vma _after_ the address, which is of questionable value
(yes, maybe you fell off the beginning, but you'd be more likely to fall
off the end).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The page-owner tracking code records stack traces during page allocation. 
To do this, it must do a memory allocation for the stack information from
inside an existing memory allocation context.  This internal allocation
must obey the high level caller allocation constraints to avoid generating
false positive warnings that have nothing to do with the code they are
instrumenting/tracking (e.g.  through lockdep reclaim state tracking)

We also don't want recording stack traces to deplete emergency memory
reserves - debug code is useless if it creates new issues that can't be
replicated when the debug code is disabled.

Switch the stack tracking allocation masking to use gfp_nested_mask() to
address these issues.  gfp_nested_mask() naturally strips GFP_ZONEMASK,
too, which greatly simplifies this code.

Link: https://lkml.kernel.org/r/20240430054604.4169568-4-david@fromorbit.com


Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "mm: fix nested allocation context filtering".

This patchset is the followup to the comment I made earlier today:

https://lore.kernel.org/linux-xfs/ZjAyIWUzDipofHFJ@dread.disaster.area/

Tl;dr: Memory allocations that are done inside the public memory
allocation API need to obey the reclaim recursion constraints placed on
the allocation by the original caller, including the "don't track
recursion for this allocation" case defined by __GFP_NOLOCKDEP.

These nested allocations are generally in debug code that is tracking
something about the allocation (kmemleak, KASAN, etc) and so are
allocating private kernel objects that only that debug system will use.

Neither the page-owner code nor the stack depot code get this right.  They
also also clear GFP_ZONEMASK as a separate operation, which is completely
redundant because the constraint filter applied immediately after
guarantees that GFP_ZONEMASK bits are cleared.

kmemleak gets this filtering right.  It preserves the allocation
constraints for deadlock prevention and clears all other context flags
whilst also ensuring that the nested allocation will fail quickly,
silently and without depleting emergency kernel reserves if there is no
memory available.

This can be made much more robust, immune to whack-a-mole games and the
code greatly simplified by lifting gfp_kmemleak_mask() to
include/linux/gfp.h and using that everywhere.  Also document it so that
there is no excuse for not knowing about it when writing new debug code
that nests allocations.

Tested with lockdep, KASAN + page_owner=on and kmemleak=on over multiple
fstests runs with XFS.


This patch (of 3):

Any "internal" nested allocation done from within an allocation context
needs to obey the high level allocation gfp_mask constraints.  This is
necessary for debug code like KASAN, kmemleak, lockdep, etc that allocate
memory for saving stack traces and other information during memory
allocation.  If they don't obey things like __GFP_NOLOCKDEP or
__GFP_NOWARN, they produce false positive failure detections.

kmemleak gets this right by using gfp_kmemleak_mask() to pass through the
relevant context flags to the nested allocation to ensure that the
allocation follows the constraints of the caller context.

KASAN recently was foudn to be missing __GFP_NOLOCKDEP due to stack depot
allocations, and even more recently the page owner tracking code was also
found to be missing __GFP_NOLOCKDEP support.

We also don't wan't want KASAN or lockdep to drive the system into OOM
kill territory by exhausting emergency reserves.  This is something that
kmemleak also gets right by adding (__GFP_NORETRY | __GFP_NOMEMALLOC |
__GFP_NOWARN) to the allocation mask.

Hence it is clear that we need to define a common nested allocation filter
mask for these sorts of third party nested allocations used in debug code.
So to start this process, lift gfp_kmemleak_mask() to gfp.h and rename it
to gfp_nested_mask(), and convert the kmemleak callers to use it.

Link: https://lkml.kernel.org/r/20240430054604.4169568-1-david@fromorbit.com
Link: https://lkml.kernel.org/r/20240430054604.4169568-2-david@fromorbit.com


Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Extend execmem parameters to accommodate more complex overrides of
module_alloc() by architectures.

This includes specification of a fallback range required by arm, arm64
and powerpc, EXECMEM_MODULE_DATA type required by powerpc, support for
allocation of KASAN shadow required by s390 and x86 and support for
late initialization of execmem required by arm64.

The core implementation of execmem_alloc() takes care of suppressing
warnings when the initial allocation fails but there is a fallback range
defined.

Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Tested-by: Liviu Dudau <liviu@dudau.co.uk>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

Several architectures override module_alloc() only to define address
range for code allocations different than VMALLOC address space.

Provide a generic implementation in execmem that uses the parameters for
address space ranges, required alignment and page protections provided
by architectures.

The architectures must fill execmem_info structure and implement
execmem_arch_setup() that returns a pointer to that structure. This way the
execmem initialization won't be called from every architecture, but rather
from a central place, namely a core_initcall() in execmem.

The execmem provides execmem_alloc() API that wraps __vmalloc_node_range()
with the parameters defined by the architectures.  If an architecture does
not implement execmem_arch_setup(), execmem_alloc() will fall back to
module_alloc().

Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

module_alloc() is used everywhere as a mean to allocate memory for code.

Beside being semantically wrong, this unnecessarily ties all subsystems
that need to allocate code, such as ftrace, kprobes and BPF to modules and
puts the burden of code allocation to the modules code.

Several architectures override module_alloc() because of various
constraints where the executable memory can be located and this causes
additional obstacles for improvements of code allocation.

Start splitting code allocation from modules by introducing execmem_alloc()
and execmem_free() APIs.

Initially, execmem_alloc() is a wrapper for module_alloc() and
execmem_free() is a replacement of module_memfree() to allow updating all
call sites to use the new APIs.

Since architectures define different restrictions on placement,
permissions, alignment and other parameters for memory that can be used by
different subsystems that allocate executable memory, execmem_alloc() takes
a type argument, that will be used to identify the calling subsystem and to
allow architectures define parameters for ranges suitable for that
subsystem.

No functional changes.

Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

Since commit 857f2139 ("memcg, oom: remove unnecessary check in
mem_cgroup_oom_synchronize()"), memcg_oom_gfp_mask and memcg_oom_order are
no longer used any more.

Link: https://lkml.kernel.org/r/20240509032628.1217652-1-xiujianfeng@huawei.com


Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Benjamin Segall <bsegall@google.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

commit 1cb9dc4b ("mm: hwpoison: support recovery from HugePage
copy-on-write faults") added support to use the mc variants when coping
hugetlb pages on CoW faults.

Add the missing VM_FAULT_SET_HINDEX, so the right si_addr_lsb will be
passed to userspace to report the extension of the faulty area.

Link: https://lkml.kernel.org/r/20240509100148.22384-3-osalvador@suse.de


Signed-off-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "Minor fixups for hugetlb fault path".

This series contains a couple of fixups for hugetlb_fault and hugetlb_wp
respectively, where a VM_FAULT_SET_HINDEX call was missing.

I did not bother with a Fixes tag because the missing piece here is that
we will not report to userspace the right extension of the faulty area by
adjusting struct kernel_siginfo.si_addr_lsb, but I do not consider that to
be a big issue because I assume that userspace already knows the size of
the mapping anyway.


This patch (of 2):

commit af19487f ("mm: make PTE_MARKER_SWAPIN_ERROR more general")
added the code to handle pte_markers in hugetlb faulting path.  In case of
an UFFD_POISON event, a PTE_MARKER_POISONED will be created and we will
return VM_FAULT_HWPOISON_LARGE upon detecting that in the fault path.  Add
the missing VM_FAULT_SET_HINDEX, so the right si_addr_lsb will be passed
to userspace to report the extension of the faulty area.

Link: https://lkml.kernel.org/r/20240509100148.22384-1-osalvador@suse.de
Link: https://lkml.kernel.org/r/20240509100148.22384-2-osalvador@suse.de


Signed-off-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

alloc_mem_cgroup_per_node_info() returns int that doesn't map to any errno
error code.  The only existing caller doesn't really need an error code so
change the function to return bool (true on success) because this is
slightly less confusing and more consistent with the other code.

Link: https://lkml.kernel.org/r/20240507132324.1158510-1-xiujianfeng@huawei.com


Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

damos_wmark_metric_value's return value is 'unsigned long', so returning
-EINVAL as 'unsigned long' may turn out to be very different from the
expected one (using 2's complement) and treat as usual matric's value. 
So, fix that, checking if returned value is not 0.

Link: https://lkml.kernel.org/r/20240506180238.53842-1-sj@kernel.org


Fixes: ee801b7d ("mm/damon/schemes: activate schemes based on a watermarks mechanism")
Signed-off-by: Alex Rusuf <yorha.op@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Previously, all NR_VM_EVENT_ITEMS stats were maintained per-memcg,
although some of those fields are not exposed anywhere. Commit
14e0f6c957e39 ("memcg: reduce memory for the lruvec and memcg stats")
changed this such that we only maintain the stats we actually expose
per-memcg via a translation table.

Additionally, commit 514462bbe927b ("memcg: warn for unexpected events
and stats") added a warning if a per-memcg stat update is attempted for
a stat that is not in the translation table. The warning started firing
for the NR_{FILE/SHMEM}_PMDMAPPED stat updates in the rmap code. These
stats are not maintained per-memcg, and hence are not in the translation
table.

Do not use __lruvec_stat_mod_folio() when updating NR_FILE_PMDMAPPED and
NR_SHMEM_PMDMAPPED. Use __mod_node_page_state() instead, which updates
the global per-node stats only.

Link: https://lkml.kernel.org/r/20240506192924.271999-1-yosryahmed@google.com


Fixes: 514462bbe927 ("memcg: warn for unexpected events and stats")
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Reported-by:  <syzbot+9319a4268a640e26b72b@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/lkml/0000000000001b9d500617c8b23c@google.com


Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "mm/damon: misc fixes and improvements".

Add miscelleneous and non-urgent fixes and improvements for DAMON code,
selftests, and documents.


This patch (of 10):

damos_quota_init_priv() function should initialize all private fields of
struct damos_quota.  However, it is not initializing ->esz_bp field.  This
could result in use of uninitialized variable from
damon_feed_loop_next_input() function.  There is no such issue at the
moment because every caller of the function is passing damos_quota object
that already having the field zero value.  But we cannot guarantee the
future, and the function is not doing what it is promising.  A bug is a
bug.  This fix is for preventing possible future issues.

Link: https://lkml.kernel.org/r/20240503180318.72798-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20240503180318.72798-2-sj@kernel.org


Fixes: 9294a037 ("mm/damon/core: implement goal-oriented feedback-driven quota auto-tuning")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

We now handle order-1 folios correctly, so we don't need this assertion
any more.

Link: https://lkml.kernel.org/r/20240429190114.3126789-1-willy@infradead.org


Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

All reclaim_folio_list() callers are passing 'true' for
'ignore_references' parameter.  In other words, the parameter is not
really being used.  Simplify the code by removing the parameter.

Link: https://lkml.kernel.org/r/20240429224451.67081-5-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

All reclaim_pages() callers are setting 'ignore_references' parameter
'true'.  In other words, the parameter is not really being used.  Remove
the argument to make it simple.

Link: https://lkml.kernel.org/r/20240429224451.67081-4-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

'pageout' DAMOS action implementation of 'paddr' DAMON operations set asks
reclaim_pages() to do page level access check if the user is not asking
DAMOS to do that on its own.  Simplify the logic by making the check
always be done by 'paddr'.

Link: https://lkml.kernel.org/r/20240429224451.67081-3-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "mm/damon/paddr: simplify page level access re-check for
pageout.

The 'pageout' DAMOS action implementation of 'paddr' asks reclaim_pages()
to do page level access check again.  But the user can ask 'paddr' to do
the page level access check on its own, using DAMOS filter of 'young page'
type.  Meanwhile, 'paddr' is the only user of reclaim_pages() that asks
the page level access check.

Make 'paddr' does the page level access check on its own always, and
simplify reclaim_pages() by removing the page level access check request
handling logic.  As a result of the change for reclaim_pages(),
reclaim_folio_list(), which is called by reclaim_pages(), also no more
need to do the page level access check.  Simplify the function, too.


This patch (of 4):

'pageout' DAMOS action implementation of 'paddr' asks reclaim_pages() to
do the page level access check.  User could ask DAMOS to do the page level
access check on its own using 'young page' type DAMOS filter.  In the
case, pageout DAMOS action unnecessarily asks reclaim_pages() to do the
check again.  Ask the page level access check only if the scheme is not
having the filter.

Link: https://lkml.kernel.org/r/20240429224451.67081-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20240429224451.67081-2-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Commit a12083d7 added hugepd handling for gup-slow, reusing gup-fast
functions.  follow_hugepd() correctly took the vma pointer in, however
didn't pass it over into the lower functions, which was overlooked.

The issue is gup_fast_hugepte() uses the vma pointer to make the correct
decision on whether an unshare is needed for a FOLL_PIN|FOLL_LONGTERM. 
Now without vma ponter it will constantly return "true" (needs an unshare)
for a page cache, even though in the SHARED case it will be wrong to
unshare.

The other problem is, even if an unshare is needed, it now returns 0
rather than -EMLINK, which will not trigger a follow up FAULT_FLAG_UNSHARE
fault.  That will need to be fixed too when the unshare is wanted.

gup_longterm test didn't expose this issue in the past because it didn't
yet test R/O unshare in this case, another separate patch will enable that
in future tests.

Fix it by passing vma correctly to the bottom, rename gup_fast_hugepte()
back to gup_hugepte() as it is shared between the fast/slow paths, and
also allow -EMLINK to be returned properly by gup_hugepte() even though
gup-fast will take it the same as zero.

Link: https://lkml.kernel.org/r/20240430131303.264331-1-peterx@redhat.com


Fixes: a12083d7 ("mm/gup: handle hugepd for follow_page()")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: David Hildenbrand <david@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Align the CMA area for hugetlb gigantic pages to their size, not the size
that they can be demoted to.  Otherwise there might be misaligned sections
at the start and end of the CMA area that will never be used for hugetlb
page allocations.

Link: https://lkml.kernel.org/r/20240430161437.2100295-1-fvdl@google.com


Fixes: a01f4390 ("hugetlb: be sure to free demoted CMA pages to CMA")
Signed-off-by: Frank van der Linden <fvdl@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

A memcg pointer in the per-cpu stock can be accessed by
drain_all_stock() and consume_stock() in parallel, causing a potential
race, which is believed to e harmless.

KCSAN shows this data-race clearly in the splat below:

	BUG: KCSAN: data-race in drain_all_stock.part.0 / try_charge_memcg

	write to 0xffff88903f8b0788 of 4 bytes by task 35901 on cpu 2:
	try_charge_memcg (mm/memcontrol.c:2323 mm/memcontrol.c:2746)
	__mem_cgroup_charge (mm/memcontrol.c:7287 mm/memcontrol.c:7301)
	do_anonymous_page (mm/memory.c:1054 mm/memory.c:4375 mm/memory.c:4433)
	__handle_mm_fault (mm/memory.c:3878 mm/memory.c:5300 mm/memory.c:5441)
	handle_mm_fault (mm/memory.c:5606)
	do_user_addr_fault (arch/x86/mm/fault.c:1363)
	exc_page_fault (./arch/x86/include/asm/irqflags.h:37
		        ./arch/x86/include/asm/irqflags.h:72
			arch/x86/mm/fault.c:1513
			arch/x86/mm/fault.c:1563)
	asm_exc_page_fault (./arch/x86/include/asm/idtentry.h:623)

	read to 0xffff88903f8b0788 of 4 bytes by task 287 on cpu 27:
	drain_all_stock.part.0 (mm/memcontrol.c:2433)
	mem_cgroup_css_offline (mm/memcontrol.c:5398 mm/memcontrol.c:5687)
	css_killed_work_fn (kernel/cgroup/cgroup.c:5521 kernel/cgroup/cgroup.c:5794)
	process_one_work (kernel/workqueue.c:3254)
	worker_thread (kernel/workqueue.c:3329 kernel/workqueue.c:3416)
	kthread (kernel/kthread.c:388)
	ret_from_fork (arch/x86/kernel/process.c:147)
	ret_from_fork_asm (arch/x86/entry/entry_64.S:257)

	value changed: 0x00000014 -> 0x00000013

This happens because drain_all_stock() is reading stock->nr_pages, while
consume_stock() might be updating the same address, causing a potential
data-race.

Make the shared addresses bulletproof regarding to reads and writes,
similarly to what stock->cached_objcg and stock->cached.
Annotate all accesses to stock->nr_pages with READ_ONCE()/WRITE_ONCE().

Link: https://lkml.kernel.org/r/20240501095420.679208-1-leitao@debian.org


Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

__split_huge_pmd_locked() can be called for a present THP, devmap or
(non-present) migration entry.  It calls pmdp_invalidate() unconditionally
on the pmdp and only determines if it is present or not based on the
returned old pmd.  This is a problem for the migration entry case because
pmd_mkinvalid(), called by pmdp_invalidate() must only be called for a
present pmd.

On arm64 at least, pmd_mkinvalid() will mark the pmd such that any future
call to pmd_present() will return true.  And therefore any lockless
pgtable walker could see the migration entry pmd in this state and start
interpretting the fields as if it were present, leading to BadThings (TM).
GUP-fast appears to be one such lockless pgtable walker.

x86 does not suffer the above problem, but instead pmd_mkinvalid() will
corrupt the offset field of the swap entry within the swap pte.  See link
below for discussion of that problem.

Fix all of this by only calling pmdp_invalidate() for a present pmd.  And
for good measure let's add a warning to all implementations of
pmdp_invalidate[_ad]().  I've manually reviewed all other
pmdp_invalidate[_ad]() call sites and believe all others to be conformant.

This is a theoretical bug found during code review.  I don't have any test
case to trigger it in practice.

Link: https://lkml.kernel.org/r/20240501143310.1381675-1-ryan.roberts@arm.com
Link: https://lore.kernel.org/all/0dd7827a-6334-439a-8fd0-43c98e6af22b@arm.com/


Fixes: 84c3fc4e ("mm: thp: check pmd migration entry in common path")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

An invalidated pmd should still cause pmd_leaf() to return true.  Let's
test for that to ensure all arches remain consistent.

Link: https://lkml.kernel.org/r/20240501144439.1389048-1-ryan.roberts@arm.com


Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

The memcg stats update functions can take arbitrary integer but the only
input which make sense is enum memcg_stat_item and we don't want these
functions to be called with arbitrary integer, so replace the parameter
type with enum memcg_stat_item and compiler will be able to warn if memcg
stat update functions are called with incorrect index value.

Link: https://lkml.kernel.org/r/20240501172617.678560-9-shakeel.butt@linux.dev


Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

To reduce memory usage by the memcg events and stats, the kernel uses
indirection table and only allocate stats and events which are being used
by the memcg code.  To make this more robust, let's add warnings where
unexpected stats and events indexes are used.

Link: https://lkml.kernel.org/r/20240501172617.678560-8-shakeel.butt@linux.dev


Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: T.J. Mercier <tjmercier@google.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

WORKINGSET_NODES is not exposed in the memcg stats and thus there is no
need to use the memcg specific stat update functions for it.  In future if
we decide to expose WORKINGSET_NODES in the memcg stats, we can revert
this patch.

Link: https://lkml.kernel.org/r/20240501172617.678560-7-shakeel.butt@linux.dev


Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

There are no memcg specific stats for NR_SHMEM_PMDMAPPED and
NR_FILE_PMDMAPPED.  Let's remove them.

Link: https://lkml.kernel.org/r/20240501172617.678560-6-shakeel.butt@linux.dev


Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

At the moment, the amount of memory allocated for stats related structs in
the mem_cgroup corresponds to the size of enum node_stat_item.  However
not all fields in enum node_stat_item have corresponding memcg stats.  So,
let's use indirection mechanism similar to the one used for memcg vmstats
management.

For a given x86_64 config, the size of stats with and without patch is:

structs size in bytes         w/o     with

struct lruvec_stats           1128     648
struct lruvec_stats_percpu     752     432
struct memcg_vmstats          1832    1352
struct memcg_vmstats_percpu   1280     960

The memory savings are further compounded by the fact that these structs
are allocated for each cpu and for each node.  To be precise, for each
memcg the memory saved would be:

Memory saved = ((21 * 3 * NR_NODES) + (21 * 2 * NR_NODES * NR_CPUS) +
	       (21 * 3) + (21 * 2 * NR_CPUS)) * sizeof(long)

Where 21 is the number of fields eliminated.

Link: https://lkml.kernel.org/r/20240501172617.678560-5-shakeel.butt@linux.dev


Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: T.J. Mercier <tjmercier@google.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

The percpu memory used by memcg's memory statistics is already accounted. 
For consistency, let's enable accounting for vmstats and lruvec stats as
well.

Link: https://lkml.kernel.org/r/20240501172617.678560-4-shakeel.butt@linux.dev


Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

To decouple the dependency of lruvec_stats on NR_VM_NODE_STAT_ITEMS, we
need to dynamically allocate lruvec_stats in the mem_cgroup_per_node
structure.  Also move the definition of lruvec_stats_percpu and
lruvec_stats and related functions to the memcontrol.c to facilitate later
patches.  No functional changes in the patch.

Link: https://lkml.kernel.org/r/20240501172617.678560-3-shakeel.butt@linux.dev


Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "memcg: reduce memory consumption by memcg stats", v4.

Most of the memory overhead of a memcg object is due to memcg stats
maintained by the kernel.  Since stats updates happen in performance
critical codepaths, the stats are maintained per-cpu and numa specific
stats are maintained per-node * per-cpu.  This drastically increase the
overhead on large machines i.e.  large of CPUs and multiple numa nodes. 
This patch series tries to reduce the overhead by at least not allocating
the memory for stats which are not memcg specific.  


This patch (of 8):

mem_cgroup_events_index is a translation table to get the right index of
the memcg relevant entry for the general vm_event_item.  At the moment, it
is defined as integer array.  However on a typical system the max entry of
vm_event_item (NR_VM_EVENT_ITEMS) is 113, so we don't need to use int as
storage type of the array.  For now just use int8_t as type and add a
BUILD_BUG_ON().

Another benefit of this change is that the translation table fits in 2
cachelines while previously it would require 8 cachelines (assuming 64
bytes cacheline).

Link: https://lkml.kernel.org/r/20240501172617.678560-1-shakeel.butt@linux.dev
Link: https://lkml.kernel.org/r/20240501172617.678560-2-shakeel.butt@linux.dev


Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Let's document why hugetlb still uses folio_mapcount() and is prone to
leaking memory between processes, for example using vmsplice() that still
uses FOLL_GET.

More details can be found in [1], especially around how hugetlb pages
cannot really be overcommitted, and why we don't particularly care about
these vmsplice() leaks for hugetlb -- in contrast to ordinary memory.

[1] https://lore.kernel.org/all/8b42a24d-caf0-46ef-9e15-0f88d47d2f21@redhat.com/

Link: https://lkml.kernel.org/r/20240502085259.103784-3-david@redhat.com


Signed-off-by: David Hildenbrand <david@redhat.com>
Suggested-by: Peter Xu <peterx@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

In scan_swap_map_slots(), si->highest_bit can by changed by
swap_range_alloc() concurrently.  All reads on si->highest_bit except one
is either protected by lock or read using READ_ONCE.  So mark the one racy
read on si->highest_bit as benign using READ_ONCE.

This patch is aimed at reducing the number of benign races reported by
KCSAN in order to focus future debugging effort on harmful races.

Link: https://lkml.kernel.org/r/tencent_912BC3E8B0291DA4A0028AB424076375DA07@qq.com


Signed-off-by: linke li <lilinke99@qq.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Change the type of we_locked from int to bool because folio_trylock return
bool

Link: https://lkml.kernel.org/r/20240428012049.8182-1-gehao@kylinos.cn


Signed-off-by: Hao Ge <gehao@kylinos.cn>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

In __folio_remove_rmap(), a large folio is added to deferred split list if
any page in a folio loses its final mapping.  But it is possible that the
folio is fully unmapped and adding it to deferred split list is
unnecessary.

For PMD-mapped THPs, that was not really an issue, because removing the
last PMD mapping in the absence of PTE mappings would not have added the
folio to the deferred split queue.

However, for PTE-mapped THPs, which are now more prominent due to mTHP,
they are always added to the deferred split queue.  One side effect is
that the THP_DEFERRED_SPLIT_PAGE stat for a PTE-mapped folio can be
unintentionally increased, making it look like there are many partially
mapped folios -- although the whole folio is fully unmapped stepwise.

Core-mm now tries batch-unmapping consecutive PTEs of PTE-mapped THPs
where possible starting from commit b06dc281 ("mm/rmap: introduce
folio_remove_rmap_[pte|ptes|pmd]()").  When it happens, a whole PTE-mapped
folio is unmapped in one go and can avoid being added to deferred split
list, reducing the THP_DEFERRED_SPLIT_PAGE noise.  But there will still be
noise when we cannot batch-unmap a complete PTE-mapped folio in one go --
or where this type of batching is not implemented yet, e.g., migration.

To avoid the unnecessary addition, folio->_nr_pages_mapped is checked to
tell if the whole folio is unmapped.  If the folio is already on deferred
split list, it will be skipped, too.

Note: commit 98046944a159 ("mm: huge_memory: add the missing
folio_test_pmd_mappable() for THP split statistics") tried to exclude mTHP
deferred split stats from THP_DEFERRED_SPLIT_PAGE, but it does not fix the
above issue.  A fully unmapped PTE-mapped order-9 THP was still added to
deferred split list and counted as THP_DEFERRED_SPLIT_PAGE, since nr is
512 (non zero), level is RMAP_LEVEL_PTE, and inside deferred_split_folio()
the order-9 folio is folio_test_pmd_mappable().

Link: https://lkml.kernel.org/r/20240502132852.862138-1-zi.yan@sent.com


Signed-off-by: Zi Yan <ziy@nvidia.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Lance Yang <ioworker0@gmail.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>