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Date: Tue, 2 Feb 2021 12:08:30 +0800
From: Huang Jianan <huangjianan@...o.com>
To: fuse-devel@...ts.sourceforge.net
Cc: huangjianan@...o.com, guoweichao@...o.com, zhangshiming@...o.com,
linux-kernel@...r.kernel.org
Subject: [PATCH] fuse: avoid deadlock when write fuse inode
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 <huangjianan@...o.com>
Signed-off-by: Guo Weichao <guoweichao@...o.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
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