linux-kernel - Re: [PATCH] f2fs: fix a deadlock in fsync

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Message-id: <1375868596.22638.35.camel@kjgkr>
Date:	Wed, 07 Aug 2013 18:43:16 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	Jim Xu <jinuxstyle@...il.com>
Cc:	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-f2fs-devel@...ts.sourceforge.net" 
	<linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [PATCH] f2fs: fix a deadlock in fsync

Hi Jin,

2013-08-07 (수), 12:23 +0800, Jim Xu:
> Hi Kim,
> 
> The patch sounds good to me.
> 
> BTW, as in the deadlock situation I noticed, I did not find any thread was doing checkpoint at that moment. The bdi writeback thread and the fsync user thread was not. Neither was the background f2fs_gc thread because there had enough free segments. Meanwhile, another user thread was blocked in the f2fs_sync_file->sync_node_pages, which, I think, is not a factor contributing to the deadlock.

I indicated one possible scenario.
As you described, many fsync calls can also consume all the fs_lock too.
Thanks,

-- 
Jaegeuk Kim
Samsung

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