From: Jaegeuk Kim Date: Fri, 19 Dec 2014 03:32:36 +0000 (-0800) Subject: f2fs: avoid double lock for cp_rwsem X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=dd802406e396c22dfb5aa0d16196f04d515be49e;p=deliverable%2Flinux.git 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 Signed-off-by: Jaegeuk Kim --- diff --git a/fs/f2fs/acl.c b/fs/f2fs/acl.c index 1ccb26bc2a0b..7f12d28ad94c 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);