The quilt patch titled
Subject: mm: userfaultfd: fix race of userfaultfd_move and swap cache
has been removed from the -mm tree. Its filename was
mm-userfaultfd-fix-race-of-userfaultfd_move-and-swap-cache.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: Kairui Song <kasong(a)tencent.com>
Subject: mm: userfaultfd: fix race of userfaultfd_move and swap cache
Date: Wed, 4 Jun 2025 23:10:38 +0800
This commit fixes two kinds of races, they may have different results:
Barry reported a BUG_ON in commit c50f8e6053b0, we may see the same
BUG_ON if the filemap lookup returned NULL and folio is added to swap
cache after that.
If another kind of race is triggered (folio changed after lookup) we
may see RSS counter is corrupted:
[ 406.893936] BUG: Bad rss-counter state mm:ffff0000c5a9ddc0
type:MM_ANONPAGES val:-1
[ 406.894071] BUG: Bad rss-counter state mm:ffff0000c5a9ddc0
type:MM_SHMEMPAGES val:1
Because the folio is being accounted to the wrong VMA.
I'm not sure if there will be any data corruption though, seems no.
The issues above are critical already.
On seeing a swap entry PTE, userfaultfd_move does a lockless swap cache
lookup, and tries to move the found folio to the faulting vma. Currently,
it relies on checking the PTE value to ensure that the moved folio still
belongs to the src swap entry and that no new folio has been added to the
swap cache, which turns out to be unreliable.
While working and reviewing the swap table series with Barry, following
existing races are observed and reproduced [1]:
In the example below, move_pages_pte is moving src_pte to dst_pte, where
src_pte is a swap entry PTE holding swap entry S1, and S1 is not in the
swap cache:
CPU1 CPU2
userfaultfd_move
move_pages_pte()
entry = pte_to_swp_entry(orig_src_pte);
// Here it got entry = S1
... < interrupted> ...
<swapin src_pte, alloc and use folio A>
// folio A is a new allocated folio
// and get installed into src_pte
<frees swap entry S1>
// src_pte now points to folio A, S1
// has swap count == 0, it can be freed
// by folio_swap_swap or swap
// allocator's reclaim.
<try to swap out another folio B>
// folio B is a folio in another VMA.
<put folio B to swap cache using S1 >
// S1 is freed, folio B can use it
// for swap out with no problem.
...
folio = filemap_get_folio(S1)
// Got folio B here !!!
... < interrupted again> ...
<swapin folio B and free S1>
// Now S1 is free to be used again.
<swapout src_pte & folio A using S1>
// Now src_pte is a swap entry PTE
// holding S1 again.
folio_trylock(folio)
move_swap_pte
double_pt_lock
is_pte_pages_stable
// Check passed because src_pte == S1
folio_move_anon_rmap(...)
// Moved invalid folio B here !!!
The race window is very short and requires multiple collisions of multiple
rare events, so it's very unlikely to happen, but with a deliberately
constructed reproducer and increased time window, it can be reproduced
easily.
This can be fixed by checking if the folio returned by filemap is the
valid swap cache folio after acquiring the folio lock.
Another similar race is possible: filemap_get_folio may return NULL, but
folio (A) could be swapped in and then swapped out again using the same
swap entry after the lookup. In such a case, folio (A) may remain in the
swap cache, so it must be moved too:
CPU1 CPU2
userfaultfd_move
move_pages_pte()
entry = pte_to_swp_entry(orig_src_pte);
// Here it got entry = S1, and S1 is not in swap cache
folio = filemap_get_folio(S1)
// Got NULL
... < interrupted again> ...
<swapin folio A and free S1>
<swapout folio A re-using S1>
move_swap_pte
double_pt_lock
is_pte_pages_stable
// Check passed because src_pte == S1
folio_move_anon_rmap(...)
// folio A is ignored !!!
Fix this by checking the swap cache again after acquiring the src_pte
lock. And to avoid the filemap overhead, we check swap_map directly [2].
The SWP_SYNCHRONOUS_IO path does make the problem more complex, but so far
we don't need to worry about that, since folios can only be exposed to the
swap cache in the swap out path, and this is covered in this patch by
checking the swap cache again after acquiring the src_pte lock.
Testing with a simple C program that allocates and moves several GB of
memory did not show any observable performance change.
Link: https://lkml.kernel.org/r/20250604151038.21968-1-ryncsn@gmail.com
Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI")
Signed-off-by: Kairui Song <kasong(a)tencent.com>
Closes: https://lore.kernel.org/linux-mm/CAMgjq7B1K=6OOrK2OUZ0-tqCzi+EJt+2_K97TPGoS… [1]
Link: https://lore.kernel.org/all/CAGsJ_4yJhJBo16XhiC-nUzSheyX-V3-nFE+tAi=8Y560K8… [2]
Reviewed-by: Lokesh Gidra <lokeshgidra(a)google.com>
Acked-by: Peter Xu <peterx(a)redhat.com>
Reviewed-by: Suren Baghdasaryan <surenb(a)google.com>
Reviewed-by: Barry Song <baohua(a)kernel.org>
Reviewed-by: Chris Li <chrisl(a)kernel.org>
Cc: Andrea Arcangeli <aarcange(a)redhat.com>
Cc: David Hildenbrand <david(a)redhat.com>
Cc: Kairui Song <kasong(a)tencent.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/userfaultfd.c | 33 +++++++++++++++++++++++++++++++--
1 file changed, 31 insertions(+), 2 deletions(-)
--- a/mm/userfaultfd.c~mm-userfaultfd-fix-race-of-userfaultfd_move-and-swap-cache
+++ a/mm/userfaultfd.c
@@ -1084,8 +1084,18 @@ static int move_swap_pte(struct mm_struc
pte_t orig_dst_pte, pte_t orig_src_pte,
pmd_t *dst_pmd, pmd_t dst_pmdval,
spinlock_t *dst_ptl, spinlock_t *src_ptl,
- struct folio *src_folio)
+ struct folio *src_folio,
+ struct swap_info_struct *si, swp_entry_t entry)
{
+ /*
+ * Check if the folio still belongs to the target swap entry after
+ * acquiring the lock. Folio can be freed in the swap cache while
+ * not locked.
+ */
+ if (src_folio && unlikely(!folio_test_swapcache(src_folio) ||
+ entry.val != src_folio->swap.val))
+ return -EAGAIN;
+
double_pt_lock(dst_ptl, src_ptl);
if (!is_pte_pages_stable(dst_pte, src_pte, orig_dst_pte, orig_src_pte,
@@ -1102,6 +1112,25 @@ static int move_swap_pte(struct mm_struc
if (src_folio) {
folio_move_anon_rmap(src_folio, dst_vma);
src_folio->index = linear_page_index(dst_vma, dst_addr);
+ } else {
+ /*
+ * Check if the swap entry is cached after acquiring the src_pte
+ * lock. Otherwise, we might miss a newly loaded swap cache folio.
+ *
+ * Check swap_map directly to minimize overhead, READ_ONCE is sufficient.
+ * We are trying to catch newly added swap cache, the only possible case is
+ * when a folio is swapped in and out again staying in swap cache, using the
+ * same entry before the PTE check above. The PTL is acquired and released
+ * twice, each time after updating the swap_map's flag. So holding
+ * the PTL here ensures we see the updated value. False positive is possible,
+ * e.g. SWP_SYNCHRONOUS_IO swapin may set the flag without touching the
+ * cache, or during the tiny synchronization window between swap cache and
+ * swap_map, but it will be gone very quickly, worst result is retry jitters.
+ */
+ if (READ_ONCE(si->swap_map[swp_offset(entry)]) & SWAP_HAS_CACHE) {
+ double_pt_unlock(dst_ptl, src_ptl);
+ return -EAGAIN;
+ }
}
orig_src_pte = ptep_get_and_clear(mm, src_addr, src_pte);
@@ -1412,7 +1441,7 @@ retry:
}
err = move_swap_pte(mm, dst_vma, dst_addr, src_addr, dst_pte, src_pte,
orig_dst_pte, orig_src_pte, dst_pmd, dst_pmdval,
- dst_ptl, src_ptl, src_folio);
+ dst_ptl, src_ptl, src_folio, si, entry);
}
out:
_
Patches currently in -mm which might be from kasong(a)tencent.com are
mm-list_lru-refactor-the-locking-code.patch
mm-shmem-swap-improve-cached-mthp-handling-and-fix-potential-hung.patch
mm-shmem-swap-avoid-redundant-xarray-lookup-during-swapin.patch
mm-shmem-swap-improve-mthp-swapin-process.patch
mm-shmem-swap-avoid-false-positive-swap-cache-lookup.patch
The quilt patch titled
Subject: mm/gup: revert "mm: gup: fix infinite loop within __get_longterm_locked"
has been removed from the -mm tree. Its filename was
mm-gup-revert-mm-gup-fix-infinite-loop-within-__get_longterm_locked.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: David Hildenbrand <david(a)redhat.com>
Subject: mm/gup: revert "mm: gup: fix infinite loop within __get_longterm_locked"
Date: Wed, 11 Jun 2025 15:13:14 +0200
After commit 1aaf8c122918 ("mm: gup: fix infinite loop within
__get_longterm_locked") we are able to longterm pin folios that are not
supposed to get longterm pinned, simply because they temporarily have the
LRU flag cleared (esp. temporarily isolated).
For example, two __get_longterm_locked() callers can race, or
__get_longterm_locked() can race with anything else that temporarily
isolates folios.
The introducing commit mentions the use case of a driver that uses
vm_ops->fault to insert pages allocated through cma_alloc() into the page
tables, assuming they can later get longterm pinned. These pages/ folios
would never have the LRU flag set and consequently cannot get isolated.
There is no known in-tree user making use of that so far, fortunately.
To handle that in the future -- and avoid retrying forever to
isolate/migrate them -- we will need a different mechanism for the CMA
area *owner* to indicate that it actually already allocated the page and
is fine with longterm pinning it. The LRU flag is not suitable for that.
Probably we can lookup the relevant CMA area and query the bitmap; we only
have have to care about some races, probably. If already allocated, we
could just allow longterm pinning)
Anyhow, let's fix the "must not be longterm pinned" problem first by
reverting the original commit.
Link: https://lkml.kernel.org/r/20250611131314.594529-1-david@redhat.com
Fixes: 1aaf8c122918 ("mm: gup: fix infinite loop within __get_longterm_locked")
Signed-off-by: David Hildenbrand <david(a)redhat.com>
Closes: https://lore.kernel.org/all/20250522092755.GA3277597@tiffany/
Reported-by: Hyesoo Yu <hyesoo.yu(a)samsung.com>
Reviewed-by: John Hubbard <jhubbard(a)nvidia.com>
Cc: Jason Gunthorpe <jgg(a)ziepe.ca>
Cc: Peter Xu <peterx(a)redhat.com>
Cc: Zhaoyang Huang <zhaoyang.huang(a)unisoc.com>
Cc: Aijun Sun <aijun.sun(a)unisoc.com>
Cc: Alistair Popple <apopple(a)nvidia.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/gup.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
--- a/mm/gup.c~mm-gup-revert-mm-gup-fix-infinite-loop-within-__get_longterm_locked
+++ a/mm/gup.c
@@ -2303,13 +2303,13 @@ static void pofs_unpin(struct pages_or_f
/*
* Returns the number of collected folios. Return value is always >= 0.
*/
-static void collect_longterm_unpinnable_folios(
+static unsigned long collect_longterm_unpinnable_folios(
struct list_head *movable_folio_list,
struct pages_or_folios *pofs)
{
+ unsigned long i, collected = 0;
struct folio *prev_folio = NULL;
bool drain_allow = true;
- unsigned long i;
for (i = 0; i < pofs->nr_entries; i++) {
struct folio *folio = pofs_get_folio(pofs, i);
@@ -2321,6 +2321,8 @@ static void collect_longterm_unpinnable_
if (folio_is_longterm_pinnable(folio))
continue;
+ collected++;
+
if (folio_is_device_coherent(folio))
continue;
@@ -2342,6 +2344,8 @@ static void collect_longterm_unpinnable_
NR_ISOLATED_ANON + folio_is_file_lru(folio),
folio_nr_pages(folio));
}
+
+ return collected;
}
/*
@@ -2418,9 +2422,11 @@ static long
check_and_migrate_movable_pages_or_folios(struct pages_or_folios *pofs)
{
LIST_HEAD(movable_folio_list);
+ unsigned long collected;
- collect_longterm_unpinnable_folios(&movable_folio_list, pofs);
- if (list_empty(&movable_folio_list))
+ collected = collect_longterm_unpinnable_folios(&movable_folio_list,
+ pofs);
+ if (!collected)
return 0;
return migrate_longterm_unpinnable_folios(&movable_folio_list, pofs);
_
Patches currently in -mm which might be from david(a)redhat.com are
fs-proc-task_mmu-fix-page_is_pfnzero-detection-for-the-huge-zero-folio.patch
mm-gup-remove-vm_bug_ons.patch
mm-gup-remove-vm_bug_ons-fix.patch
mm-huge_memory-dont-ignore-queried-cachemode-in-vmf_insert_pfn_pud.patch
mm-huge_memory-dont-mark-refcounted-folios-special-in-vmf_insert_folio_pmd.patch
mm-huge_memory-dont-mark-refcounted-folios-special-in-vmf_insert_folio_pud.patch
After commit d5c8d6e0fa61 ("kbuild: Update assembler calls to use proper
flags and language target"), which updated as-instr to use the
'assembler-with-cpp' language option, the Kbuild version of as-instr
always fails internally for arch/arm with
<command-line>: fatal error: asm/unified.h: No such file or directory
compilation terminated.
because '-include' flags are now taken into account by the compiler
driver and as-instr does not have '$(LINUXINCLUDE)', so unified.h is not
found.
This went unnoticed at the time of the Kbuild change because the last
use of as-instr in Kbuild that arch/arm could reach was removed in 5.7
by commit 541ad0150ca4 ("arm: Remove 32bit KVM host support") but a
stable backport of the Kbuild change to before that point exposed this
potential issue if one were to be reintroduced.
Follow the general pattern of '-include' paths throughout the tree and
make unified.h absolute using '$(srctree)' to ensure KBUILD_AFLAGS can
be used independently.
Cc: stable(a)vger.kernel.org
Fixes: d5c8d6e0fa61 ("kbuild: Update assembler calls to use proper flags and language target")
Reported-by: KernelCI bot <bot(a)kernelci.org>
Closes: https://lore.kernel.org/CACo-S-1qbCX4WAVFA63dWfHtrRHZBTyyr2js8Lx=Az03XHTTHg…
Signed-off-by: Nathan Chancellor <nathan(a)kernel.org>
---
arch/arm/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 4808d3ed98e4..e31e95ffd33f 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -149,7 +149,7 @@ endif
# Need -Uarm for gcc < 3.x
KBUILD_CPPFLAGS +=$(cpp-y)
KBUILD_CFLAGS +=$(CFLAGS_ABI) $(CFLAGS_ISA) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -msoft-float -Uarm
-KBUILD_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_ISA) -Wa,$(arch-y) $(tune-y) -include asm/unified.h -msoft-float
+KBUILD_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_ISA) -Wa,$(arch-y) $(tune-y) -include $(srctree)/arch/arm/include/asm/unified.h -msoft-float
KBUILD_RUSTFLAGS += --target=arm-unknown-linux-gnueabi
CHECKFLAGS += -D__arm__
---
base-commit: e04c78d86a9699d136910cfc0bdcf01087e3267e
change-id: 20250618-arm-expand-include-unified-h-path-60e65adcda1e
Best regards,
--
Nathan Chancellor <nathan(a)kernel.org>
From: Renato Caldas <renato(a)calgera.com>
[ Upstream commit 36e66be874a7ea9d28fb9757629899a8449b8748 ]
The scancodes for the Mic Mute and Airplane keys on the Ideapad Pro 5
(14AHP9 at least, probably the other variants too) are different and
were not being picked up by the driver. This adds them to the keymap.
Apart from what is already supported, the remaining fn keys are
unfortunately producing windows-specific key-combos.
Signed-off-by: Renato Caldas <renato(a)calgera.com>
Link: https://lore.kernel.org/r/20241102183116.30142-1-renato@calgera.com
Reviewed-by: Hans de Goede <hdegoede(a)redhat.com>
Signed-off-by: Hans de Goede <hdegoede(a)redhat.com>
Signed-off-by: WangYuli <wangyuli(a)uniontech.com>
---
drivers/platform/x86/ideapad-laptop.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/platform/x86/ideapad-laptop.c b/drivers/platform/x86/ideapad-laptop.c
index 88eefccb6ed2..50013af0537c 100644
--- a/drivers/platform/x86/ideapad-laptop.c
+++ b/drivers/platform/x86/ideapad-laptop.c
@@ -1101,6 +1101,9 @@ static const struct key_entry ideapad_keymap[] = {
{ KE_KEY, 0x27 | IDEAPAD_WMI_KEY, { KEY_HELP } },
/* Refresh Rate Toggle */
{ KE_KEY, 0x0a | IDEAPAD_WMI_KEY, { KEY_DISPLAYTOGGLE } },
+ /* Specific to some newer models */
+ { KE_KEY, 0x3e | IDEAPAD_WMI_KEY, { KEY_MICMUTE } },
+ { KE_KEY, 0x3f | IDEAPAD_WMI_KEY, { KEY_RFKILL } },
{ KE_END },
};
--
2.50.0