mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-10 04:29:11 -04:00
a564ccfe30
When update_mmu_cache_range() is called by update_mmu_cache(), the vmf
parameter is NULL, which will cause a NULL pointer dereference issue in
adjust_pte():
Unable to handle kernel NULL pointer dereference at virtual address 00000030 when read
Hardware name: Atmel AT91SAM9
PC is at update_mmu_cache_range+0x1e0/0x278
LR is at pte_offset_map_rw_nolock+0x18/0x2c
Call trace:
update_mmu_cache_range from remove_migration_pte+0x29c/0x2ec
remove_migration_pte from rmap_walk_file+0xcc/0x130
rmap_walk_file from remove_migration_ptes+0x90/0xa4
remove_migration_ptes from migrate_pages_batch+0x6d4/0x858
migrate_pages_batch from migrate_pages+0x188/0x488
migrate_pages from compact_zone+0x56c/0x954
compact_zone from compact_node+0x90/0xf0
compact_node from kcompactd+0x1d4/0x204
kcompactd from kthread+0x120/0x12c
kthread from ret_from_fork+0x14/0x38
Exception stack(0xc0d8bfb0 to 0xc0d8bff8)
To fix it, do not rely on whether 'ptl' is equal to decide whether to hold
the pte lock, but decide it by whether CONFIG_SPLIT_PTE_PTLOCKS is
enabled. In addition, if two vmas map to the same PTE page, there is no
need to hold the pte lock again, otherwise a deadlock will occur. Just
add the need_lock parameter to let adjust_pte() know this information.
Link: https://lkml.kernel.org/r/20250217024924.57996-1-zhengqi.arch@bytedance.com
Fixes: fc9c45b71f ("arm: adjust_pte() use pte_offset_map_rw_nolock()")
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reported-by: Ezra Buehler <ezra.buehler@husqvarnagroup.com>
Closes: https://lore.kernel.org/lkml/CAM1KZSmZ2T_riHvay+7cKEFxoPgeVpHkVFTzVVEQ1BO0cLkHEQ@mail.gmail.com/
Acked-by: David Hildenbrand <david@redhat.com>
Tested-by: Ezra Buehler <ezra.buehler@husqvarnagroup.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.