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Date: Fri, 1 Jul 2016 12:53:39 -0400 From: Theodore Ts'o <tytso@....edu> To: Jan Kara <jack@...e.cz> Cc: linux-ext4@...r.kernel.org, Eryu Guan <eguan@...hat.com>, stable@...r.kernel.org Subject: Re: [PATCH 1/4] ext4: Fix deadlock during page writeback On Fri, Jul 01, 2016 at 11:09:50AM +0200, Jan Kara wrote: > But it is not safe - the bio contains pages, those pages have PageWriteback > set and if the inode is part of the running transaction, > ext4_journal_stop() will wait for transaction commit which will wait for > all outstanding writeback on the inode, which will deadlock on those pages > which are part of our unsubmitted bio. So the ordering really has to be the > way it is... So to be clear. the issue is that PageWriteback won't get cleared until we potentially do a uninit->init conversion, and this is what requires taking a transaction handle leading to the other half of the deadlock? ... and it's probably not safe to clear the PageWriteback early in the bio completion callback function, isn't it. Hmm.... - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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