Revert "mm/compaction: fix set skip in fast_find_migrateblock"
This reverts commit 7efc3b72. We have got openSUSE reports (Link 1) for 6.1 kernel with khugepaged stalling CPU for long periods of time. Investigation of tracepoint data shows that compaction is stuck in repeating fast_find_migrateblock() based migrate page isolation, and then fails to migrate all isolated pages. Commit 7efc3b72 ("mm/compaction: fix set skip in fast_find_migrateblock") was suspected as it was merged in 6.1 and in theory can indeed remove a termination condition for fast_find_migrateblock() under certain conditions, as it removes a place that always marks a scanned pageblock from being re-scanned. There are other such places, but those can be skipped under certain conditions, which seems to match the tracepoint data. Testing of revert also appears to have resolved the issue, thus revert the commit until a more robust solution for the original problem is developed. It's also likely this will fix qemu stalls with 6.1 kernel reported in Link 2, but that is not yet confirmed. Link: https://bugzilla.suse.com/show_bug.cgi?id=1206848 Link: https://lore.kernel.org/kvm/b8017e09-f336-3035-8344-c549086c2340@kernel.org/ Link: https://lore.kernel.org/lkml/20230125134434.18017-1-mgorman@techsingularity.net/ Fixes: 7efc3b72 ("mm/compaction: fix set skip in fast_find_migrateblock") Cc: <stable@vger.kernel.org> Tested-by: Pedro Falcato <pedro.falcato@gmail.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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