[merged mm-hotfixes-stable] mm-shmem-fix-getting-incorrect-lruvec-when-replacing-a-shmem-folio.patch removed from -mm tree

[merged mm-hotfixes-stable] mm-shmem-fix-getting-incorrect-lruvec-when-replacing-a-shmem-folio.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm: shmem: fix getting incorrect lruvec when replacing a shmem folio
has been removed from the -mm tree.  Its filename was
     mm-shmem-fix-getting-incorrect-lruvec-when-replacing-a-shmem-folio.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Baolin Wang <baolin.wang@linux.alibaba.com>
Subject: mm: shmem: fix getting incorrect lruvec when replacing a shmem folio
Date: Thu, 13 Jun 2024 16:21:19 +0800

When testing shmem swapin, I encountered the warning below on my machine. 
The reason is that replacing an old shmem folio with a new one causes
mem_cgroup_migrate() to clear the old folio's memcg data.  As a result,
the old folio cannot get the correct memcg's lruvec needed to remove
itself from the LRU list when it is being freed.  This could lead to
possible serious problems, such as LRU list crashes due to holding the
wrong LRU lock, and incorrect LRU statistics.

To fix this issue, we can fallback to use the mem_cgroup_replace_folio()
to replace the old shmem folio.

[ 5241.100311] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5d9960
[ 5241.100317] head: order:4 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
[ 5241.100319] flags: 0x17fffe0000040068(uptodate|lru|head|swapbacked|node=0|zone=2|lastcpupid=0x3ffff)
[ 5241.100323] raw: 17fffe0000040068 fffffdffd6687948 fffffdffd69ae008 0000000000000000
[ 5241.100325] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
[ 5241.100326] head: 17fffe0000040068 fffffdffd6687948 fffffdffd69ae008 0000000000000000
[ 5241.100327] head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
[ 5241.100328] head: 17fffe0000000204 fffffdffd6665801 ffffffffffffffff 0000000000000000
[ 5241.100329] head: 0000000a00000010 0000000000000000 00000000ffffffff 0000000000000000
[ 5241.100330] page dumped because: VM_WARN_ON_ONCE_FOLIO(!memcg && !mem_cgroup_disabled())
[ 5241.100338] ------------[ cut here ]------------
[ 5241.100339] WARNING: CPU: 19 PID: 78402 at include/linux/memcontrol.h:775 folio_lruvec_lock_irqsave+0x140/0x150
[...]
[ 5241.100374] pc : folio_lruvec_lock_irqsave+0x140/0x150
[ 5241.100375] lr : folio_lruvec_lock_irqsave+0x138/0x150
[ 5241.100376] sp : ffff80008b38b930
[...]
[ 5241.100398] Call trace:
[ 5241.100399]  folio_lruvec_lock_irqsave+0x140/0x150
[ 5241.100401]  __page_cache_release+0x90/0x300
[ 5241.100404]  __folio_put+0x50/0x108
[ 5241.100406]  shmem_replace_folio+0x1b4/0x240
[ 5241.100409]  shmem_swapin_folio+0x314/0x528
[ 5241.100411]  shmem_get_folio_gfp+0x3b4/0x930
[ 5241.100412]  shmem_fault+0x74/0x160
[ 5241.100414]  __do_fault+0x40/0x218
[ 5241.100417]  do_shared_fault+0x34/0x1b0
[ 5241.100419]  do_fault+0x40/0x168
[ 5241.100420]  handle_pte_fault+0x80/0x228
[ 5241.100422]  __handle_mm_fault+0x1c4/0x440
[ 5241.100424]  handle_mm_fault+0x60/0x1f0
[ 5241.100426]  do_page_fault+0x120/0x488
[ 5241.100429]  do_translation_fault+0x4c/0x68
[ 5241.100431]  do_mem_abort+0x48/0xa0
[ 5241.100434]  el0_da+0x38/0xc0
[ 5241.100436]  el0t_64_sync_handler+0x68/0xc0
[ 5241.100437]  el0t_64_sync+0x14c/0x150
[ 5241.100439] ---[ end trace 0000000000000000 ]---

[baolin.wang@linux.alibaba.com: remove less helpful comments, per Matthew]
  Link: https://lkml.kernel.org/r/ccad3fe1375b468ebca3227b6b729f3eaf9d8046.1718423197.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/3c11000dd6c1df83015a8321a859e9775ebbc23e.1718266112.git.baolin.wang@linux.alibaba.com
Fixes: 85ce2c517ade ("memcontrol: only transfer the memcg data for migration")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memcontrol.c |    3 +--
 mm/shmem.c      |    2 +-
 2 files changed, 2 insertions(+), 3 deletions(-)

--- a/mm/memcontrol.c~mm-shmem-fix-getting-incorrect-lruvec-when-replacing-a-shmem-folio
+++ a/mm/memcontrol.c
@@ -7745,8 +7745,7 @@ void __mem_cgroup_uncharge_folios(struct
  * @new: Replacement folio.
  *
  * Charge @new as a replacement folio for @old. @old will
- * be uncharged upon free. This is only used by the page cache
- * (in replace_page_cache_folio()).
+ * be uncharged upon free.
  *
  * Both folios must be locked, @new->mapping must be set up.
  */
--- a/mm/shmem.c~mm-shmem-fix-getting-incorrect-lruvec-when-replacing-a-shmem-folio
+++ a/mm/shmem.c
@@ -1786,7 +1786,7 @@ static int shmem_replace_folio(struct fo
 	xa_lock_irq(&swap_mapping->i_pages);
 	error = shmem_replace_entry(swap_mapping, swap_index, old, new);
 	if (!error) {
-		mem_cgroup_migrate(old, new);
+		mem_cgroup_replace_folio(old, new);
 		__lruvec_stat_mod_folio(new, NR_FILE_PAGES, 1);
 		__lruvec_stat_mod_folio(new, NR_SHMEM, 1);
 		__lruvec_stat_mod_folio(old, NR_FILE_PAGES, -1);
_

Patches currently in -mm which might be from baolin.wang@linux.alibaba.com are

mm-memory-extend-finish_fault-to-support-large-folio.patch
mm-memory-extend-finish_fault-to-support-large-folio-fix.patch
mm-memory-extend-finish_fault-to-support-large-folio-fix-fix.patch
mm-shmem-add-thp-validation-for-pmd-mapped-thp-related-statistics.patch
mm-shmem-add-multi-size-thp-sysfs-interface-for-anonymous-shmem.patch
mm-shmem-add-multi-size-thp-sysfs-interface-for-anonymous-shmem-fix.patch
mm-shmem-add-mthp-support-for-anonymous-shmem.patch
mm-shmem-add-mthp-size-alignment-in-shmem_get_unmapped_area.patch
mm-shmem-add-mthp-counters-for-anonymous-shmem.patch
mm-shmem-add-mthp-counters-for-anonymous-shmem-fix.patch
mm-memcontrol-add-vm_bug_on_folio-to-catch-lru-folio-in-mem_cgroup_migrate.patch