From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaegeuk Kim Subject: Re: [f2fs-dev] [PATCH 6/6 v2] f2fs: avoid double lock for cp_rwsem Date: Tue, 23 Dec 2014 11:08:38 -0800 Message-ID: <20141223190838.GA13638@jaegeuk-mac02> References: <1419179723-3234-1-git-send-email-jaegeuk@kernel.org> <1419179723-3234-6-git-send-email-jaegeuk@kernel.org> <003201d01e7e$66126ae0$323740a0$@samsung.com> <20141223074041.GB9946@jaegeuk-mac02.hsd1.ca.comcast.net> <003801d01e8e$c496f080$4dc4d180$@samsung.com> <20141223190537.GB12880@jaegeuk-mac02> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20141223190537.GB12880@jaegeuk-mac02> Sender: linux-fsdevel-owner@vger.kernel.org To: Chao Yu Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net List-Id: linux-f2fs-devel.lists.sourceforge.net Change log from v1: o fix description >>From fc897d61c01acc19dba434cd4aa29baeb1537b60 Mon Sep 17 00:00:00 2001 From: Jaegeuk Kim 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 Signed-off-by: Jaegeuk Kim --- 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