[Ocfs2-devel] [PATCH] ocfs2: Avoid livelock in ocfs2_readpage()

[Joel Becker]

On Thu, Jun 23, 2011 at 10:51:47PM +0200, Jan Kara wrote:
> When someone writes to an inode, readers accessing the same inode via
> ocfs2_readpage() just busyloop trying to get ip_alloc_sem because
> do_generic_file_read() looks up the page again and retries ->readpage()
> when previous attempt failed with AOP_TRUNCATED_PAGE. When there are enough
> readers, they can occupy all CPUs and in non-preempt kernel the system is
> deadlocked because writer holding ip_alloc_sem is never run to release the
> semaphore. Fix the problem by making reader block on ip_alloc_sem to break
> the busy loop.
> 
> Signed-off-by: Jan Kara <jack at suse.cz>

This patch is now in the fixes branch of ocfs2.git.

Joel

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