From: Chao Yu <yuchao0@huawei.com>
To: <jaegeuk@kernel.org>
Cc: <linux-f2fs-devel@lists.sourceforge.net>,
<linux-kernel@vger.kernel.org>, <chao@kernel.org>,
<drosen@google.com>, Chao Yu <yuchao0@huawei.com>
Subject: [PATCH] f2fs: fix to drop meta/node pages during umount
Date: Thu, 18 Jul 2019 16:39:59 +0800 [thread overview]
Message-ID: <20190718083959.32321-1-yuchao0@huawei.com> (raw)
As reported in bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=204193
A null pointer dereference bug is triggered in f2fs under kernel-5.1.3.
kasan_report.cold+0x5/0x32
f2fs_write_end_io+0x215/0x650
bio_endio+0x26e/0x320
blk_update_request+0x209/0x5d0
blk_mq_end_request+0x2e/0x230
lo_complete_rq+0x12c/0x190
blk_done_softirq+0x14a/0x1a0
__do_softirq+0x119/0x3e5
irq_exit+0x94/0xe0
call_function_single_interrupt+0xf/0x20
During umount, we will access NULL sbi->node_inode pointer in
f2fs_write_end_io():
f2fs_bug_on(sbi, page->mapping == NODE_MAPPING(sbi) &&
page->index != nid_of_node(page));
The reason is if disable_checkpoint mount option is on, meta dirty
pages can remain during umount, and then be flushed by iput() of
meta_inode, however node_inode has been iput()ed before
meta_inode's iput().
Since checkpoint is disabled, all meta/node datas are useless and
should be dropped in next mount, so in umount, let's adjust
drop_inode() to give a hint to iput_final() to drop all those dirty
datas correctly.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
fs/f2fs/super.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 580fa3d837c7..e5cae67935f6 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -873,7 +873,21 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
static int f2fs_drop_inode(struct inode *inode)
{
+ struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
int ret;
+
+ /*
+ * during filesystem shutdown, if checkpoint is disabled,
+ * drop useless meta/node dirty pages.
+ */
+ if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
+ if (inode->i_ino == F2FS_NODE_INO(sbi) ||
+ inode->i_ino == F2FS_META_INO(sbi)) {
+ trace_f2fs_drop_inode(inode, 1);
+ return 1;
+ }
+ }
+
/*
* This is to avoid a deadlock condition like below.
* writeback_single_inode(inode)
--
2.18.0.rc1
reply other threads:[~2019-07-18 8:40 UTC|newest]
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