Messages in this thread Patch in this message | | | Date | Fri, 31 Dec 2021 13:04:27 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH v4 1/1] mm: vmscan: Reduce throttling due to a failure to make progress |
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On Fri, 31 Dec 2021 11:21:14 -0800 Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Fri, Dec 31, 2021 at 11:14 AM Linus Torvalds > <torvalds@linux-foundation.org> wrote: > > > > On Fri, Dec 31, 2021 at 6:24 AM Thorsten Leemhuis > > <regressions@leemhuis.info> wrote: > > > > > > If we get it into rc8 (which is still possible, even if a bit hard due > > > to the new year festivities), it will get at least one week of testing. > > > > I took it with Hugh's ack from his reply to this, so it should be in rc8. > > Pushed out as 1b4e3f26f9f7 ("mm: vmscan: Reduce throttling due to a > failure to make progress")
Needs this fixup, which I shall tweak a bit then send formally in a few minutes.
From: Mel Gorman <mgorman@techsingularity.net> Subject: mm: vmscan: reduce throttling due to a failure to make progress -fix
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.
This is a fix to the mmotm patch mm-vmscan-reduce-throttling-due-to-a-failure-to-make-progress.patch
Link: https://lkml.kernel.org/r/20211209095453.GM3366@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reported-by: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Rik van Riel <riel@surriel.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Darrick J. Wong <djwong@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> ---
mm/vmscan.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/vmscan.c~mm-vmscan-reduce-throttling-due-to-a-failure-to-make-progress-fix +++ a/mm/vmscan.c @@ -3530,7 +3530,8 @@ static void shrink_zones(struct zonelist shrink_node(zone->zone_pgdat, sc); } - consider_reclaim_throttle(first_pgdat, sc); + if (first_pgdat) + consider_reclaim_throttle(first_pgdat, sc); /* * Restore to original mask to avoid the impact on the caller if we _
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