The patch titled
Subject: mm: memory-failure: update ttu flag inside unmap_poisoned_folio
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-memory-failure-update-ttu-flag-inside-unmap_poisoned_folio.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memory-failure-update-ttu-flag-inside-unmap_poisoned_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: mm: memory-failure: update ttu flag inside unmap_poisoned_folio
Date: Mon, 17 Feb 2025 09:43:27 +0800
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 ]---
Link: https://lkml.kernel.org/r/20250217014329.3610326-1-mawupeng1@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20250217014329.3610326-2-mawupeng1@xxxxxxxxxx
Fixes: 6da6b1d4a7df ("mm/hwpoison: convert TTU_IGNORE_HWPOISON to TTU_HWPOISON")
Signed-off-by: Ma Wupeng <mawupeng1@xxxxxxxxxx>
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Ma Wupeng <mawupeng1@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/internal.h | 5 ++-
mm/memory-failure.c | 61 +++++++++++++++++++++---------------------
mm/memory_hotplug.c | 3 +-
3 files changed, 36 insertions(+), 33 deletions(-)
--- a/mm/internal.h~mm-memory-failure-update-ttu-flag-inside-unmap_poisoned_folio
+++ a/mm/internal.h
@@ -1115,7 +1115,7 @@ static inline int find_next_best_node(in
* mm/memory-failure.c
*/
#ifdef CONFIG_MEMORY_FAILURE
-void unmap_poisoned_folio(struct folio *folio, enum ttu_flags ttu);
+int unmap_poisoned_folio(struct folio *folio, unsigned long pfn, bool must_kill);
void shake_folio(struct folio *folio);
extern int hwpoison_filter(struct page *p);
@@ -1138,8 +1138,9 @@ unsigned long page_mapped_in_vma(const s
struct vm_area_struct *vma);
#else
-static inline void unmap_poisoned_folio(struct folio *folio, enum ttu_flags ttu)
+static inline int unmap_poisoned_folio(struct folio *folio, unsigned long pfn, bool must_kill)
{
+ return -EBUSY;
}
#endif
--- a/mm/memory-failure.c~mm-memory-failure-update-ttu-flag-inside-unmap_poisoned_folio
+++ a/mm/memory-failure.c
@@ -1556,8 +1556,34 @@ static int get_hwpoison_page(struct page
return ret;
}
-void unmap_poisoned_folio(struct folio *folio, enum ttu_flags ttu)
+int unmap_poisoned_folio(struct folio *folio, unsigned long pfn, bool must_kill)
{
+ enum ttu_flags ttu = TTU_IGNORE_MLOCK | TTU_SYNC | TTU_HWPOISON;
+ struct address_space *mapping;
+
+ if (folio_test_swapcache(folio)) {
+ pr_err("%#lx: keeping poisoned page in swap cache\n", pfn);
+ ttu &= ~TTU_HWPOISON;
+ }
+
+ /*
+ * Propagate the dirty bit from PTEs to struct page first, because we
+ * need this to decide if we should kill or just drop the page.
+ * XXX: the dirty test could be racy: set_page_dirty() may not always
+ * be called inside page lock (it's recommended but not enforced).
+ */
+ mapping = folio_mapping(folio);
+ if (!must_kill && !folio_test_dirty(folio) && mapping &&
+ mapping_can_writeback(mapping)) {
+ if (folio_mkclean(folio)) {
+ folio_set_dirty(folio);
+ } else {
+ ttu &= ~TTU_HWPOISON;
+ pr_info("%#lx: corrupted page was clean: dropped without side effects\n",
+ pfn);
+ }
+ }
+
if (folio_test_hugetlb(folio) && !folio_test_anon(folio)) {
struct address_space *mapping;
@@ -1572,7 +1598,7 @@ void unmap_poisoned_folio(struct folio *
if (!mapping) {
pr_info("%#lx: could not lock mapping for mapped hugetlb folio\n",
folio_pfn(folio));
- return;
+ return -EBUSY;
}
try_to_unmap(folio, ttu|TTU_RMAP_LOCKED);
@@ -1580,6 +1606,8 @@ void unmap_poisoned_folio(struct folio *
} else {
try_to_unmap(folio, ttu);
}
+
+ return folio_mapped(folio) ? -EBUSY : 0;
}
/*
@@ -1589,8 +1617,6 @@ void unmap_poisoned_folio(struct folio *
static bool hwpoison_user_mappings(struct folio *folio, struct page *p,
unsigned long pfn, int flags)
{
- enum ttu_flags ttu = TTU_IGNORE_MLOCK | TTU_SYNC | TTU_HWPOISON;
- struct address_space *mapping;
LIST_HEAD(tokill);
bool unmap_success;
int forcekill;
@@ -1613,29 +1639,6 @@ static bool hwpoison_user_mappings(struc
if (!folio_mapped(folio))
return true;
- if (folio_test_swapcache(folio)) {
- pr_err("%#lx: keeping poisoned page in swap cache\n", pfn);
- ttu &= ~TTU_HWPOISON;
- }
-
- /*
- * Propagate the dirty bit from PTEs to struct page first, because we
- * need this to decide if we should kill or just drop the page.
- * XXX: the dirty test could be racy: set_page_dirty() may not always
- * be called inside page lock (it's recommended but not enforced).
- */
- mapping = folio_mapping(folio);
- if (!(flags & MF_MUST_KILL) && !folio_test_dirty(folio) && mapping &&
- mapping_can_writeback(mapping)) {
- if (folio_mkclean(folio)) {
- folio_set_dirty(folio);
- } else {
- ttu &= ~TTU_HWPOISON;
- pr_info("%#lx: corrupted page was clean: dropped without side effects\n",
- pfn);
- }
- }
-
/*
* First collect all the processes that have the page
* mapped in dirty form. This has to be done before try_to_unmap,
@@ -1643,9 +1646,7 @@ static bool hwpoison_user_mappings(struc
*/
collect_procs(folio, p, &tokill, flags & MF_ACTION_REQUIRED);
- unmap_poisoned_folio(folio, ttu);
-
- unmap_success = !folio_mapped(folio);
+ unmap_success = !unmap_poisoned_folio(folio, pfn, flags & MF_MUST_KILL);
if (!unmap_success)
pr_err("%#lx: failed to unmap page (folio mapcount=%d)\n",
pfn, folio_mapcount(folio));
--- a/mm/memory_hotplug.c~mm-memory-failure-update-ttu-flag-inside-unmap_poisoned_folio
+++ a/mm/memory_hotplug.c
@@ -1833,7 +1833,8 @@ static void do_migrate_range(unsigned lo
if (WARN_ON(folio_test_lru(folio)))
folio_isolate_lru(folio);
if (folio_mapped(folio))
- unmap_poisoned_folio(folio, TTU_IGNORE_MLOCK);
+ unmap_poisoned_folio(folio, pfn, false);
+
continue;
}
_
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
