diff options
| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2025-11-28 04:00:58 +0000 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-11-29 10:41:11 -0800 |
| commit | faf3c923523e5c8fc3baaa413d62e913774ae52f (patch) | |
| tree | aac01d72a6257e18f2163cebba9d95f21327807a /mm | |
| parent | b60a3ef7848dbcc9549137f8d42dcd82210c0b66 (diff) | |
mm: fix vma_start_write_killable() signal handling
If we get a signal, we need to restore the vm_refcnt. We don't think that
the refcount can actually be decremented to zero here as it requires the
VMA to be detached, and the vma_mark_detached() uses TASK_UNINTERRUPTIBLE.
However, that's a bit subtle, so handle it as if the refcount was zero at
the start of this function.
Link: https://lkml.kernel.org/r/20251128040100.3022561-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: syzbot+5b19bad23ac7f44bf8b8@syzkaller.appspotmail.com
Fixes: 2197bb60f890 ("mm: add vma_start_write_killable()")
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/mmap_lock.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c index e6e5570d1ec7..7421b7ea8001 100644 --- a/mm/mmap_lock.c +++ b/mm/mmap_lock.c @@ -74,6 +74,14 @@ static inline int __vma_enter_locked(struct vm_area_struct *vma, refcount_read(&vma->vm_refcnt) == tgt_refcnt, state); if (err) { + if (refcount_sub_and_test(VMA_LOCK_OFFSET, &vma->vm_refcnt)) { + /* + * The wait failed, but the last reader went away + * as well. Tell the caller the VMA is detached. + */ + WARN_ON_ONCE(!detaching); + err = 0; + } rwsem_release(&vma->vmlock_dep_map, _RET_IP_); return err; } |