* Antigen forwarded attachment
@ 2012-09-19 18:51 Antigen_SEAXCH01
0 siblings, 0 replies; 2+ messages in thread
From: Antigen_SEAXCH01 @ 2012-09-19 18:51 UTC (permalink / raw)
To: kosaki.motohiro; +Cc: minchan, akpm, linux-mm, linux-kernel, mgorman
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The body from the message "Re: [PATCH] mm: fix NR_ISOLATED_[ANON|FILE] mismatch", originally sent to you by linux-kernel-owner@vger.kernel.org (linux-kernel-owner@vger.kernel.org), has been forwarded to you from the Antigen Quarantine area.
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<<Body of Message>>
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On Wed, Sep 19, 2012 at 01:04:56PM -0400, KOSAKI Motohiro wrote:
> On Wed, Sep 19, 2012 at 3:45 AM, Minchan Kim <minchan@kernel.org> wrote:
> > When I looked at zone stat mismatch problem, I found
> > migrate_to_node doesn't decrease NR_ISOLATED_[ANON|FILE]
> > if check_range fails.
This is a bit misleading. It's not that the stats would be
inaccurate, it's that the pages would be leaked from the LRU, no?
> > It can make system hang out.
Did you spot this by code review only or did you actually run into
this? Because...
> > Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> > Cc: Mel Gorman <mgorman@suse.de>
> > Cc: Christoph Lameter <cl@linux.com>
> > Signed-off-by: Minchan Kim <minchan@kernel.org>
> > ---
> > mm/mempolicy.c | 16 ++++++++--------
> > 1 file changed, 8 insertions(+), 8 deletions(-)
> >
> > diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> > index 3d64b36..6bf0860 100644
> > --- a/mm/mempolicy.c
> > +++ b/mm/mempolicy.c
> > @@ -953,16 +953,16 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest,
> >
> > vma = check_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
> > flags | MPOL_MF_DISCONTIG_OK, &pagelist);
> > - if (IS_ERR(vma))
> > - return PTR_ERR(vma);
> > -
> > - if (!list_empty(&pagelist)) {
> > + if (IS_ERR(vma)) {
> > + err = PTR_ERR(vma);
> > + goto out;
> > + }
> > + if (!list_empty(&pagelist))
> > err = migrate_pages(&pagelist, new_node_page, dest,
> > false, MIGRATE_SYNC);
> > - if (err)
> > - putback_lru_pages(&pagelist);
> > - }
> > -
> > +out:
> > + if (err)
> > + putback_lru_pages(&pagelist);
>
> Good catch!
> This is a regression since following commit. So, I doubt we need
> all or nothing semantics. Can we revert it instead? (and probably
> we need more kind comment for preventing an accident)
I think it makes sense to revert. Not because of the semantics, but I
just don't see how check_range() could even fail for this callsite:
1. we pass mm->mmap->vm_start in there, so we should not fail due to
find_vma()
2. we pass MPOL_MF_DISCONTIG_OK, so the discontig checks do not apply
and so can not fail
3. we pass MPOL_MF_MOVE | MPOL_MF_MOVE_ALL, the page table loops will
continue until addr == end, so we never fail with -EIO
> commit 0def08e3acc2c9c934e4671487029aed52202d42
> Author: Vasiliy Kulikov <segooon@gmail.com>
> Date: Tue Oct 26 14:21:32 2010 -0700
>
> mm/mempolicy.c: check return code of check_range
We don't use this code to "check" the range, we use it to collect
migrate pages. There is no failure case.
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Antigen forwarded attachment
@ 2012-09-19 19:08 Antigen_SEAXCH01
0 siblings, 0 replies; 2+ messages in thread
From: Antigen_SEAXCH01 @ 2012-09-19 19:08 UTC (permalink / raw)
To: akpm
Cc: linux-mm, linux-kernel, minchan, kamezawa.hiroyu, isimatu.yasuaki,
wency, shli
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The body from the message "[PATCH] memory-hotplug: fix zone stat mismatch", originally sent to you by linux-kernel-owner@vger.kernel.org (linux-kernel-owner@vger.kernel.org), has been forwarded to you from the Antigen Quarantine area.
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<<Body of Message>>
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During memory-hotplug stress test, I found NR_ISOLATED_[ANON|FILE]
are increasing so that kernel are hang out.
The cause is that when we do memory-hotadd after memory-remove,
__zone_pcp_update clear out zone's ZONE_STAT_ITEMS in setup_pageset
without draining vm_stat_diff of all CPU.
This patch fixes it.
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Shaohua Li <shli@fusionio.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
Andrew, I think it's a candidate of stable but didn't Cced
stable.
Please send this patch to stable if reviewer couldn't find
any fault when you merge.
Thanks.
include/linux/vmstat.h | 4 ++++
mm/page_alloc.c | 1 +
mm/vmstat.c | 12 ++++++++++++
3 files changed, 17 insertions(+)
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index ad2cfd5..5d31876 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -198,6 +198,8 @@ extern void __dec_zone_state(struct zone *, enum zone_stat_item);
void refresh_cpu_vm_stats(int);
void refresh_zone_stat_thresholds(void);
+void drain_zonestat(struct zone *zone, struct per_cpu_pageset *);
+
int calculate_pressure_threshold(struct zone *zone);
int calculate_normal_threshold(struct zone *zone);
void set_pgdat_percpu_threshold(pg_data_t *pgdat,
@@ -251,6 +253,8 @@ static inline void __dec_zone_page_state(struct page *page,
static inline void refresh_cpu_vm_stats(int cpu) { }
static inline void refresh_zone_stat_thresholds(void) { }
+static inline void drain_zonestat(struct zone *zone,
+ struct per_cpu_pageset *pset) { }
#endif /* CONFIG_SMP */
extern const char * const vmstat_text[];
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ab58346..5d005c8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5904,6 +5904,7 @@ static int __meminit __zone_pcp_update(void *data)
local_irq_save(flags);
if (pcp->count > 0)
free_pcppages_bulk(zone, pcp->count, pcp);
+ drain_zonestat(zone, pset);
setup_pageset(pset, batch);
local_irq_restore(flags);
}
diff --git a/mm/vmstat.c b/mm/vmstat.c
index b3e3b9d..d4cc1c2 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -495,6 +495,18 @@ void refresh_cpu_vm_stats(int cpu)
atomic_long_add(global_diff[i], &vm_stat[i]);
}
+void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset)
+{
+ int i;
+
+ for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
+ if (pset->vm_stat_diff[i]) {
+ int v = pset->vm_stat_diff[i];
+ pset->vm_stat_diff[i] = 0;
+ atomic_long_add(v, &zone->vm_stat[i]);
+ atomic_long_add(v, &vm_stat[i]);
+ }
+}
#endif
#ifdef CONFIG_NUMA
--
1.7.9.5
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