| Message ID | 1308305213-4657-3-git-send-email-colin.king@canonical.com |
|---|---|
| State | New |
| Headers | show |
On 06/17/2011 11:06 AM, Colin King wrote: > From: Johannes Weiner<hannes@cmpxchg.org> > > There are a few reports of people experiencing hangs when copying large > amounts of data with kswapd using a large amount of CPU which appear to be > due to recent reclaim changes. SLUB using high orders is the trigger but > not the root cause as SLUB has been using high orders for a while. The > root cause was bugs introduced into reclaim which are addressed by the > following two patches. > > Patch 1 corrects logic introduced by commit 1741c877 ("mm: kswapd: > keep kswapd awake for high-order allocations until a percentage of > the node is balanced") to allow kswapd to go to sleep when > balanced for high orders. > > Patch 2 notes that it is possible for kswapd to miss every > cond_resched() and updates shrink_slab() so it'll at least reach > that scheduling point. > > Chris Wood reports that these two patches in isolation are sufficient to > prevent the system hanging. AFAIK, they should also resolve similar hangs > experienced by James Bottomley. > > This patch: > > Johannes Weiner poined out that the logic in commit 1741c877 ("mm: kswapd: > keep kswapd awake for high-order allocations until a percentage of the > node is balanced") is backwards. Instead of allowing kswapd to go to > sleep when balancing for high order allocations, it keeps it kswapd > running uselessly. > > Signed-off-by: Mel Gorman<mgorman@suse.de> > Reviewed-by: Rik van Riel<riel@redhat.com> > Signed-off-by: Johannes Weiner<hannes@cmpxchg.org> > Reviewed-by: Wu Fengguang<fengguang.wu@intel.com> > Cc: James Bottomley<James.Bottomley@HansenPartnership.com> > Tested-by: Colin King<colin.king@canonical.com> > Cc: Raghavendra D Prabhu<raghu.prabhu13@gmail.com> > Cc: Jan Kara<jack@suse.cz> > Cc: Chris Mason<chris.mason@oracle.com> > Cc: Christoph Lameter<cl@linux.com> > Cc: Pekka Enberg<penberg@kernel.org> > Cc: Rik van Riel<riel@redhat.com> > Reviewed-by: Minchan Kim<minchan.kim@gmail.com> > Reviewed-by: Wu Fengguang<fengguang.wu@intel.com> > Cc:<stable@kernel.org> [2.6.38+] > Signed-off-by: Andrew Morton<akpm@linux-foundation.org> > Signed-off-by: Linus Torvalds<torvalds@linux-foundation.org> > --- > mm/vmscan.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 648aab8..a74bf72 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2291,7 +2291,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining, > * must be balanced > */ > if (order) > - return pgdat_balanced(pgdat, balanced, classzone_idx); > + return !pgdat_balanced(pgdat, balanced, classzone_idx); > else > return !all_zones_ok; > } Acked-by: Brad Figg <brad.figg@canonical.com>
On Fri, Jun 17, 2011 at 11:06:53AM +0100, Colin King wrote: > From: Johannes Weiner <hannes@cmpxchg.org> > > There are a few reports of people experiencing hangs when copying large > amounts of data with kswapd using a large amount of CPU which appear to be > due to recent reclaim changes. SLUB using high orders is the trigger but > not the root cause as SLUB has been using high orders for a while. The > root cause was bugs introduced into reclaim which are addressed by the > following two patches. > > Patch 1 corrects logic introduced by commit 1741c877 ("mm: kswapd: > keep kswapd awake for high-order allocations until a percentage of > the node is balanced") to allow kswapd to go to sleep when > balanced for high orders. > > Patch 2 notes that it is possible for kswapd to miss every > cond_resched() and updates shrink_slab() so it'll at least reach > that scheduling point. > > Chris Wood reports that these two patches in isolation are sufficient to > prevent the system hanging. AFAIK, they should also resolve similar hangs > experienced by James Bottomley. > > This patch: > > Johannes Weiner poined out that the logic in commit 1741c877 ("mm: kswapd: > keep kswapd awake for high-order allocations until a percentage of the > node is balanced") is backwards. Instead of allowing kswapd to go to > sleep when balancing for high order allocations, it keeps it kswapd > running uselessly. > > Signed-off-by: Mel Gorman <mgorman@suse.de> > Reviewed-by: Rik van Riel <riel@redhat.com> > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> > Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> > Cc: James Bottomley <James.Bottomley@HansenPartnership.com> > Tested-by: Colin King <colin.king@canonical.com> > Cc: Raghavendra D Prabhu <raghu.prabhu13@gmail.com> > Cc: Jan Kara <jack@suse.cz> > Cc: Chris Mason <chris.mason@oracle.com> > Cc: Christoph Lameter <cl@linux.com> > Cc: Pekka Enberg <penberg@kernel.org> > Cc: Rik van Riel <riel@redhat.com> > Reviewed-by: Minchan Kim <minchan.kim@gmail.com> > Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> > Cc: <stable@kernel.org> [2.6.38+] > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> > --- > mm/vmscan.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 648aab8..a74bf72 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2291,7 +2291,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining, > * must be balanced > */ > if (order) > - return pgdat_balanced(pgdat, balanced, classzone_idx); > + return !pgdat_balanced(pgdat, balanced, classzone_idx); > else > return !all_zones_ok; > } Acked-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com> > -- > 1.7.0.4 > > > -- > kernel-team mailing list > kernel-team@lists.ubuntu.com > https://lists.ubuntu.com/mailman/listinfo/kernel-team >
diff --git a/mm/vmscan.c b/mm/vmscan.c index 648aab8..a74bf72 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2291,7 +2291,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining, * must be balanced */ if (order) - return pgdat_balanced(pgdat, balanced, classzone_idx); + return !pgdat_balanced(pgdat, balanced, classzone_idx); else return !all_zones_ok; }