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Mel Gorman
8008293888
Hugh Dickins reported the following
My tmpfs swapping load (tweaked to use huge pages more heavily
than in real life) is far from being a realistic load: but it was
notably slowed down by your throttling mods in 5.16-rc, and this
patch makes it well again - thanks.
But: it very quickly hit NULL pointer until I changed that last
line to
if (first_pgdat)
consider_reclaim_throttle(first_pgdat, sc);
The likely issue is that huge pages are a major component of the test
workload. When this is the case, first_pgdat may never get set if
compaction is ready to continue due to this check
if (IS_ENABLED(CONFIG_COMPACTION) &&
sc->order > PAGE_ALLOC_COSTLY_ORDER &&
compaction_ready(zone, sc)) {
sc->compaction_ready = true;
continue;
}
If this was true for every zone in the zonelist, first_pgdat would never
get set resulting in a NULL pointer exception.
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 1b4e3f26f9 ("mm: vmscan: Reduce throttling due to a failure to make progress")
Signed-off-by: Mel Gorman <[email protected]>
Reported-by: Hugh Dickins <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Darrick J. Wong <[email protected]>
Cc: Shakeel Butt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>