Hello, we were recently debugging an issue where customer was hitting warnings in xfs_vm_releasepage() which was complaining that the page it was called for has delay-allocated buffers. After some debugging we realized that indeed try_to_release_page() call from shrink_active_list() can happen for a page in arbitrary state (that call happens only if buffer_heads_over_limit is set so that is the reason why we normally don't see that). Hence comes my question: What are the rules for when can ->releasepage() be called? And what is the expected outcome? We are certainly guaranteed to hold page lock. try_to_release_page() also makes sure the page isn't under writeback. But what is ->releasepage() supposed to do with a dirty page? Generally IFAIU we aren't supposed to discard dirty data but I wouldn't bet on all filesystems getting it right because the common call paths make sure page is clean. I would almost say we should enforce !PageDirty in try_to_release_page() if it was not for that ext3 nastyness of cleaning buffers under a dirty page - hum, but maybe the right answer for that is ripping ext3 out of tree (which would also allow us to get rid of some code in the blocklayer for bouncing journaled data buffers when stable writes are required). Thoughts? Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
