Messages in this thread Patch in this message | | | Date | Mon, 26 Nov 2012 13:32:42 -0500 | From | Johannes Weiner <> | Subject | Re: 3.7-rc6 soft lockup in kswapd0 |
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Hi George,
On Mon, Nov 26, 2012 at 08:05:04AM -0500, George Spelvin wrote: > Mel Gorman <mgorman@suse.de> wrote: > > Ok, can you try this patch from Rik on top as well please? This is in > > addition to Dave Hansen's accounting fix. > > > > ---8<--- > > From: Rik van Riel <riel@redhat.com> > > Subject: mm,vmscan: only loop back if compaction would fail in all zones > > Booted and running. Judging from the patch, the expected result is > "stops hanging", as opposed to more informative diagnostics, so I'll > keep you posted. > > Peraonally, I like to use "bool" for such flags where possible; > it helps document the intent of the variable better.
Any chance you could test with this fix instead, in addition to Dave's accounting fix? It's got bool and everything!
--- From: Johannes Weiner <hannes@cmpxchg.org> Subject: [patch] mm: vmscan: fix endless loop in kswapd balancing
Kswapd does not in all places have the same criteria for when it considers a zone balanced. This leads to zones being not reclaimed because they are considered just fine and other checks to loop over the zonelist again because they are considered unbalanced.
Add a function, zone_balanced(), that checks the watermark, and, for higher order allocations, if compaction has enough free memory. Then use it uniformly for when kswapd needs to check if a zone is balanced.
Reported-by: George Spelvin <linux@horizon.com> Reported-by: Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Tested-by: Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: stable@kernel.org [3.4+] --- mm/vmscan.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c index 48550c6..3b0aef4 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2397,6 +2397,19 @@ static void age_active_anon(struct zone *zone, struct scan_control *sc) } while (memcg); } +static bool zone_balanced(struct zone *zone, int order, + unsigned long balance_gap, int classzone_idx) +{ + if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone) + + balance_gap, classzone_idx, 0)) + return false; + + if (COMPACTION_BUILD && order && !compaction_suitable(zone, order)) + return false; + + return true; +} + /* * pgdat_balanced is used when checking if a node is balanced for high-order * allocations. Only zones that meet watermarks and are in a zone allowed @@ -2475,8 +2488,7 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining, continue; } - if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone), - i, 0)) + if (!zone_balanced(zone, order, 0, i)) all_zones_ok = false; else balanced += zone->present_pages; @@ -2585,8 +2597,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, break; } - if (!zone_watermark_ok_safe(zone, order, - high_wmark_pages(zone), 0, 0)) { + if (!zone_balanced(zone, order, 0, 0)) { end_zone = i; break; } else { @@ -2662,9 +2673,8 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, testorder = 0; if ((buffer_heads_over_limit && is_highmem_idx(i)) || - !zone_watermark_ok_safe(zone, testorder, - high_wmark_pages(zone) + balance_gap, - end_zone, 0)) { + !zone_balanced(zone, testorder, + balance_gap, end_zone)) { shrink_zone(zone, &sc); reclaim_state->reclaimed_slab = 0; @@ -2691,8 +2701,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, continue; } - if (!zone_watermark_ok_safe(zone, testorder, - high_wmark_pages(zone), end_zone, 0)) { + if (!zone_balanced(zone, testorder, 0, end_zone)) { all_zones_ok = 0; /* * We are still under min water mark. This -- 1.7.11.7
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