| From: Glauber Costa <glommer@parallels.com> |
| Date: Wed, 25 Apr 2012 16:01:48 -0700 |
| Subject: fs/buffer.c: remove BUG() in possible but rare condition |
| |
| commit 61065a30af8df4b8989c2ac7a1f4b4034e4df2d5 upstream. |
| |
| While stressing the kernel with with failing allocations today, I hit the |
| following chain of events: |
| |
| alloc_page_buffers(): |
| |
| bh = alloc_buffer_head(GFP_NOFS); |
| if (!bh) |
| goto no_grow; <= path taken |
| |
| grow_dev_page(): |
| bh = alloc_page_buffers(page, size, 0); |
| if (!bh) |
| goto failed; <= taken, consequence of the above |
| |
| and then the failed path BUG()s the kernel. |
| |
| The failure is inserted a litte bit artificially, but even then, I see no |
| reason why it should be deemed impossible in a real box. |
| |
| Even though this is not a condition that we expect to see around every |
| time, failed allocations are expected to be handled, and BUG() sounds just |
| too much. As a matter of fact, grow_dev_page() can return NULL just fine |
| in other circumstances, so I propose we just remove it, then. |
| |
| Signed-off-by: Glauber Costa <glommer@parallels.com> |
| Cc: Michal Hocko <mhocko@suse.cz> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| fs/buffer.c | 1 - |
| 1 file changed, 1 deletion(-) |
| |
| diff --git a/fs/buffer.c b/fs/buffer.c |
| index 36d6665..351e18e 100644 |
| --- a/fs/buffer.c |
| +++ b/fs/buffer.c |
| @@ -985,7 +985,6 @@ grow_dev_page(struct block_device *bdev, sector_t block, |
| return page; |
| |
| failed: |
| - BUG(); |
| unlock_page(page); |
| page_cache_release(page); |
| return NULL; |
