The patch titled
Subject: mm: convert partially_mapped set/clear operations to be atomic
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-convert-partially_mapped-set-clear-operations-to-be-atomic.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-convert-partially_mapped-set-clear-operations-to-be-atomic.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: Usama Arif <usamaarif642@xxxxxxxxx>
Subject: mm: convert partially_mapped set/clear operations to be atomic
Date: Thu, 12 Dec 2024 18:33:51 +0000
Other page flags in the 2nd page, like PG_hwpoison and PG_anon_exclusive
can get modified concurrently. Changes to other page flags might be lost
if they are happening at the same time as non-atomic partially_mapped
operations. Hence, make partially_mapped operations atomic.
Link: https://lkml.kernel.org/r/20241212183351.1345389-1-usamaarif642@xxxxxxxxx
Fixes: 8422acdc97ed ("mm: introduce a pageflag for partially mapped folios")
Reported-by: David Hildenbrand <david@xxxxxxxxxx>
Link: https://lore.kernel.org/all/e53b04ad-1827-43a2-a1ab-864c7efecf6e@xxxxxxxxxx/
Signed-off-by: Usama Arif <usamaarif642@xxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Barry Song <baohua@xxxxxxxxxx>
Cc: Domenico Cerasuolo <cerasuolodomenico@xxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
Cc: Nico Pache <npache@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/page-flags.h | 12 ++----------
mm/huge_memory.c | 8 ++++----
2 files changed, 6 insertions(+), 14 deletions(-)
--- a/include/linux/page-flags.h~mm-convert-partially_mapped-set-clear-operations-to-be-atomic
+++ a/include/linux/page-flags.h
@@ -862,18 +862,10 @@ static inline void ClearPageCompound(str
ClearPageHead(page);
}
FOLIO_FLAG(large_rmappable, FOLIO_SECOND_PAGE)
-FOLIO_TEST_FLAG(partially_mapped, FOLIO_SECOND_PAGE)
-/*
- * PG_partially_mapped is protected by deferred_split split_queue_lock,
- * so its safe to use non-atomic set/clear.
- */
-__FOLIO_SET_FLAG(partially_mapped, FOLIO_SECOND_PAGE)
-__FOLIO_CLEAR_FLAG(partially_mapped, FOLIO_SECOND_PAGE)
+FOLIO_FLAG(partially_mapped, FOLIO_SECOND_PAGE)
#else
FOLIO_FLAG_FALSE(large_rmappable)
-FOLIO_TEST_FLAG_FALSE(partially_mapped)
-__FOLIO_SET_FLAG_NOOP(partially_mapped)
-__FOLIO_CLEAR_FLAG_NOOP(partially_mapped)
+FOLIO_FLAG_FALSE(partially_mapped)
#endif
#define PG_head_mask ((1UL << PG_head))
--- a/mm/huge_memory.c~mm-convert-partially_mapped-set-clear-operations-to-be-atomic
+++ a/mm/huge_memory.c
@@ -3577,7 +3577,7 @@ int split_huge_page_to_list_to_order(str
!list_empty(&folio->_deferred_list)) {
ds_queue->split_queue_len--;
if (folio_test_partially_mapped(folio)) {
- __folio_clear_partially_mapped(folio);
+ folio_clear_partially_mapped(folio);
mod_mthp_stat(folio_order(folio),
MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1);
}
@@ -3689,7 +3689,7 @@ bool __folio_unqueue_deferred_split(stru
if (!list_empty(&folio->_deferred_list)) {
ds_queue->split_queue_len--;
if (folio_test_partially_mapped(folio)) {
- __folio_clear_partially_mapped(folio);
+ folio_clear_partially_mapped(folio);
mod_mthp_stat(folio_order(folio),
MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1);
}
@@ -3733,7 +3733,7 @@ void deferred_split_folio(struct folio *
spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
if (partially_mapped) {
if (!folio_test_partially_mapped(folio)) {
- __folio_set_partially_mapped(folio);
+ folio_set_partially_mapped(folio);
if (folio_test_pmd_mappable(folio))
count_vm_event(THP_DEFERRED_SPLIT_PAGE);
count_mthp_stat(folio_order(folio), MTHP_STAT_SPLIT_DEFERRED);
@@ -3826,7 +3826,7 @@ static unsigned long deferred_split_scan
} else {
/* We lost race with folio_put() */
if (folio_test_partially_mapped(folio)) {
- __folio_clear_partially_mapped(folio);
+ folio_clear_partially_mapped(folio);
mod_mthp_stat(folio_order(folio),
MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1);
}
_
Patches currently in -mm which might be from usamaarif642@xxxxxxxxx are
mm-convert-partially_mapped-set-clear-operations-to-be-atomic.patch
