We found the following deadlock situations in low memory scenarios:
Thread A Thread B
- __writeback_single_inode
- fuse_write_inode
- fuse_simple_request
- __fuse_request_send
- request_wait_answer
- fuse_dev_splice_read
- fuse_copy_fill
- __alloc_pages_direct_reclaim
- do_shrink_slab
- super_cache_scan
- shrink_dentry_list
- dentry_unlink_inode
- iput_final
- inode_wait_for_writeback
The request and inode processed by Thread A and B are the same, which
causes a deadlock. To avoid this, we remove the __GFP_FS flag when
allocating memory in fuse_copy_fill, so there will be no memory
reclaimation in super_cache_scan.
Signed-off-by: Huang Jianan <huangjia...@oppo.com>
Signed-off-by: Guo Weichao <guoweic...@oppo.com>
---
fs/fuse/dev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 588f8d1240aa..e580b9d04c25 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -721,7 +721,7 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
if (cs->nr_segs >= cs->pipe->max_usage)
return -EIO;
- page = alloc_page(GFP_HIGHUSER);
+ page = alloc_page(GFP_HIGHUSER & ~__GFP_FS);
if (!page)
return -ENOMEM;
--
2.25.1
