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Brian Foster authored
XFS has had scattered reports of delalloc blocks present at ->releasepage() time. This results in a warning with a stack trace similar to the following: ... Call Trace: [<ffffffffa23c5b8f>] dump_stack+0x63/0x84 [<ffffffffa20837a7>] warn_slowpath_common+0x97/0xe0 [<ffffffffa208380a>] warn_slowpath_null+0x1a/0x20 [<ffffffffa2326caf>] xfs_vm_releasepage+0x10f/0x140 [<ffffffffa218c680>] ? page_mkclean_one+0xd0/0xd0 [<ffffffffa218d3a0>] ? anon_vma_prepare+0x150/0x150 [<ffffffffa21521c2>] try_to_release_page+0x32/0x50 [<ffffffffa2166b2e>] shrink_active_list+0x3ce/0x3e0 [<ffffffffa21671c7>] shrink_lruvec+0x687/0x7d0 [<ffffffffa21673ec>] shrink_zone+0xdc/0x2c0 [<ffffffffa2168539>] kswapd+0x4f9/0x970 [<ffffffffa2168040>] ? mem_cgroup_shrink_node_zone+0x1a0/0x1a0 [<ffffffffa20a0d99>] kthread+0xc9/0xe0 [<ffffffffa20a0cd0>] ? kthread_stop+0x100/0x100 [<ffffffffa26b404f>] ret_from_fork+0x3f/0x70 [<ffffffffa20a0cd0>] ? kthread_stop+0x100/0x100 This occurs because it is possible for shrink_active_list() to send pages marked dirty to ->releasepage() when certain buffer_head threshold conditions are met. shrink_active_list() doesn't check the page dirty state apparently to handle an old ext3 corner case where in some cases clean pages would not have the dirty bit cleared, thus it is up to the filesystem to determine how to handle the page. XFS currently handles the delalloc case properly, but this behavior makes the warning spurious. Update the XFS ->releasepage() handler to explicitly skip dirty pages. Retain the existing delalloc/unwritten checks so we continue to warn if such buffers exist on clean pages when they shouldn't. Diagnosed-by:
Dave Chinner <david@fromorbit.com> Signed-off-by:
Brian Foster <bfoster@redhat.com> Reviewed-by:
Dave Chinner <dchinner@redhat.com> Signed-off-by:
Dave Chinner <david@fromorbit.com>
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