The patch titled
Subject: hwpoison, memory_hotplug: lock folio before unmap hwpoisoned folio
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
hwpoison-memory_hotplug-lock-folio-before-unmap-hwpoisoned-folio.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/hwpoison-memory_hotplug-lock-folio-before-unmap-hwpoisoned-folio.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Ma Wupeng <mawupeng1@xxxxxxxxxx>
Subject: hwpoison, memory_hotplug: lock folio before unmap hwpoisoned folio
Date: Mon, 17 Feb 2025 09:43:29 +0800
Commit b15c87263a69 ("hwpoison, memory_hotplug: allow hwpoisoned pages to
be offlined) add page poison checks in do_migrate_range in order to make
offline hwpoisoned page possible by introducing isolate_lru_page and
try_to_unmap for hwpoisoned page. However folio lock must be held before
calling try_to_unmap. Add it to fix this problem.
Warning will be produced if folio is not locked during unmap:
------------[ cut here ]------------
kernel BUG at ./include/linux/swapops.h:400!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:
CPU: 4 UID: 0 PID: 411 Comm: bash Tainted: G W 6.13.0-rc1-00016-g3c434c7ee82a-dirty #41
Tainted: [W]=WARN
Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
pstate: 40400005 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : try_to_unmap_one+0xb08/0xd3c
lr : try_to_unmap_one+0x3dc/0xd3c
Call trace:
try_to_unmap_one+0xb08/0xd3c (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
Code: f9407be0 b5fff320 d4210000 17ffff97 (d4210000)
---[ end trace 0000000000000000 ]---
Link: https://lkml.kernel.org/r/20250217014329.3610326-4-mawupeng1@xxxxxxxxxx
Fixes: b15c87263a69 ("hwpoison, memory_hotplug: allow hwpoisoned pages to be offlined")
Signed-off-by: Ma Wupeng <mawupeng1@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Naoya Horiguchi <nao.horiguchi@xxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/mm/memory_hotplug.c~hwpoison-memory_hotplug-lock-folio-before-unmap-hwpoisoned-folio
+++ a/mm/memory_hotplug.c
@@ -1832,8 +1832,11 @@ static void do_migrate_range(unsigned lo
(folio_test_large(folio) && folio_test_has_hwpoisoned(folio))) {
if (WARN_ON(folio_test_lru(folio)))
folio_isolate_lru(folio);
- if (folio_mapped(folio))
+ if (folio_mapped(folio)) {
+ folio_lock(folio);
unmap_poisoned_folio(folio, pfn, false);
+ folio_unlock(folio);
+ }
goto put_folio;
}
_
Patches currently in -mm which might be from mawupeng1@xxxxxxxxxx are
mm-memory-failure-update-ttu-flag-inside-unmap_poisoned_folio.patch
mm-memory-hotplug-check-folio-ref-count-first-in-do_migrate_range.patch
hwpoison-memory_hotplug-lock-folio-before-unmap-hwpoisoned-folio.patch
