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Sasha Levin b051f70701 mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE 
commit 9614d8bee6 upstream.

With CONFIG_HIGHPTE on 32-bit ARM, move_pages_pte() maps PTE pages using
kmap_local_page(), which requires unmapping in Last-In-First-Out order.

The current code maps dst_pte first, then src_pte, but unmaps them in the
same order (dst_pte, src_pte), violating the LIFO requirement.  This
causes the warning in kunmap_local_indexed():

  WARNING: CPU: 0 PID: 604 at mm/highmem.c:622 kunmap_local_indexed+0x178/0x17c
  addr \!= __fix_to_virt(FIX_KMAP_BEGIN + idx)

Fix this by reversing the unmap order to respect LIFO ordering.

This issue follows the same pattern as similar fixes:
- commit eca6828403 ("crypto: skcipher - fix mismatch between mapping and unmapping order")
- commit 8cf57c6df8 ("nilfs2: eliminate staggered calls to kunmap in nilfs_rename")

Both of which addressed the same fundamental requirement that kmap_local
operations must follow LIFO ordering.

Link: https://lkml.kernel.org/r/20250731144431.773923-1-sashal@kernel.org
Fixes: adef440691 ("userfaultfd: UFFDIO_MOVE uABI")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-09-09 18:58:15 +02:00
arch x86/mm/64: define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() 2025-09-09 18:58:15 +02:00
block
certs
crypto
Documentation
drivers pcmcia: Fix a NULL pointer dereference in __iodyn_find_io_region() 2025-09-09 18:58:15 +02:00
fs
include io_uring/msg_ring: ensure io_kiocb freeing is deferred for RCU 2025-09-09 18:58:15 +02:00
init
io_uring io_uring/msg_ring: ensure io_kiocb freeing is deferred for RCU 2025-09-09 18:58:15 +02:00
ipc
kernel
lib
LICENSES
mm mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE 2025-09-09 18:58:15 +02:00
net net: atm: fix memory leak in atm_register_sysfs when device_register fail 2025-09-09 18:58:13 +02:00
rust
samples
scripts
security
sound ALSA: usb-audio: Add mute TLV for playback volumes on some devices 2025-09-09 18:58:14 +02:00
tools selftest: net: Fix weird setsockopt() in bind_bhash.c. 2025-09-09 18:58:14 +02:00
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