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Subject[PATCH] fs/afs/flock and fs/locks: Fix possible sleep-in-atomic bugs in posix_lock_file
Date
The kernel may sleep under a spinlock, and the function call paths are:
afs_do_unlk (acquire the spinlock)
posix_lock_file
posix_lock_inode (fs/locks.c)
locks_get_lock_context
kmem_cache_alloc(GFP_KERNEL) --> may sleep

afs_do_setlk (acquire the spinlock)
posix_lock_file
posix_lock_inode (fs/locks.c)
locks_get_lock_context
kmem_cache_alloc(GFP_KERNEL) --> may sleep

To fix them, GFP_KERNEL is replaced with GFP_ATOMIC.
These bugs are found by my static analysis tool and my code review.

Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
---
fs/locks.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/locks.c b/fs/locks.c
index 1bd71c4..975cc62 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -222,7 +222,7 @@ struct file_lock_list_struct {
if (likely(ctx) || type == F_UNLCK)
goto out;

- ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
+ ctx = kmem_cache_alloc(flctx_cache, GFP_ATOMIC);
if (!ctx)
goto out;

--
1.7.9.5

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