Messages in this thread Patch in this message | | | Date | Tue, 23 Dec 2014 11:08:38 -0800 | From | Jaegeuk Kim <> | Subject | Re: [f2fs-dev] [PATCH 6/6 v2] f2fs: avoid double lock for cp_rwsem |
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Change log from v1: o fix description
From fc897d61c01acc19dba434cd4aa29baeb1537b60 Mon Sep 17 00:00:00 2001 From: Jaegeuk Kim <jaegeuk@kernel.org> Date: Thu, 18 Dec 2014 19:32:36 -0800 Subject: [PATCH] f2fs: avoid double lock for cp_rwsem
The __f2fs_add_link is covered by cp_rwsem all the time. This calls init_inode_metadata, which conducts some acl operations including memory allocation with GFP_KERNEL previously. But, under memory pressure, f2fs_write_data_page can be called, which also grabs cp_rwsem too.
In this case, this incurs a deadlock pointed by Chao. Thread #1 Thread #2 down_read down_write down_read -> here down_read should wait forever.
Reviewed-by: Chao Yu <chao2.yu@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> --- fs/f2fs/acl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/acl.c b/fs/f2fs/acl.c index 1ccb26b..7f12d28 100644 --- a/fs/f2fs/acl.c +++ b/fs/f2fs/acl.c @@ -62,7 +62,7 @@ static struct posix_acl *f2fs_acl_from_disk(const char *value, size_t size) if (count == 0) return NULL; - acl = posix_acl_alloc(count, GFP_KERNEL); + acl = posix_acl_alloc(count, GFP_NOFS); if (!acl) return ERR_PTR(-ENOMEM); @@ -116,7 +116,7 @@ static void *f2fs_acl_to_disk(const struct posix_acl *acl, size_t *size) int i; f2fs_acl = kmalloc(sizeof(struct f2fs_acl_header) + acl->a_count * - sizeof(struct f2fs_acl_entry), GFP_KERNEL); + sizeof(struct f2fs_acl_entry), GFP_NOFS); if (!f2fs_acl) return ERR_PTR(-ENOMEM); -- 2.1.1
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