Re: Easy portable testcase! (Re: Kernel falls apart under lightmemory pressure (i.e. linking vmlinux))
From: Minchan Kim
Date: Sun May 29 2011 - 14:28:57 EST
On Fri, May 27, 2011 at 8:58 AM, Minchan Kim <minchan.kim@xxxxxxxxx> wrote:
> On Thu, May 26, 2011 at 5:17 AM, Andrew Lutomirski <luto@xxxxxxx> wrote:
>> On Tue, May 24, 2011 at 8:43 PM, KOSAKI Motohiro
>> <kosaki.motohiro@xxxxxxxxxxxxxx> wrote:
>>>
>>> Unfortnately, this log don't tell us why DM don't issue any swap io. ;-)
>>> I doubt it's DM issue. Can you please try to make swap on out of DM?
>>>
>>>
>>
>> I can do one better: I can tell you how to reproduce the OOM in the
>> comfort of your own VM without using dm_crypt or a Sandy Bridge
>> laptop. ÂThis is on Fedora 15, but it really ought to work on any
>> x86_64 distribution that has kvm. ÂYou'll probably want at least 6GB
>> on your host machine because the VM wants 4GB ram.
>>
>> Here's how:
>>
>> Step 1: Clone git://gitorious.org/linux-test-utils/reproduce-annoying-mm-bug.git
>>
>> (You can browse here:)
>> https://gitorious.org/linux-test-utils/reproduce-annoying-mm-bug
>>
>> Instructions to reproduce the mm bug:
>>
>> Step 2: Build Linux v2.6.38.6 with config-2.6.38.6 and the patch
>> 0001-Minchan-patch-for-testing-23-05-2011.patch (both files are in the
>> git repo)
>>
>> Step 3: cd back to reproduce-annoying-mm-bug
>>
>> Step 4: Type this.
>>
>> $ make
>> $ qemu-kvm -m 4G -smp 2 -kernel <linux_dir>/arch/x86/boot/bzImage
>> -initrd initramfs.gz
>>
>> Step 5: Wait for the VM to boot (it's really fast) and then run ./repro_bug.sh.
>>
>> Step 6: Wait a bit and watch the fireworks. ÂNote that it can take a
>> couple minutes to reproduce the bug.
>>
>> Tested on my Sandy Bridge laptop and on a Xeon W3520.
>>
>> For whatever reason, on my laptop without the VM I can hit the bug
>> almost instantaneously. ÂMaybe it's because I'm using dm-crypt on my
>> laptop.
>>
>> --Andy
>>
>> P.S. ÂI think that the mk_trivial_initramfs.sh script is cute, and
>
> That's cool. :)
>
>> maybe I'll try to flesh it out and turn it into a real project some
>> day.
>>
>
> Thanks for good test environment.
> Yesterday, I tried to reproduce your problem in my system(4G DRAM) but
> unfortunately got failed. I tried various setting but I can't reach.
> Maybe I need 8G system or sandy-bridge. Â:(
>
> Hi mm folks, It's next round.
> Andrew Lutomirski's first problem, kswapd hang problem was solved by
> recent Mel's series(!pgdat_balanced bug and shrink_slab cond_resched)
> which is key for James, Collins problem.
>
> Andrew's next problem is a early OOM kill.
>
> [ Â 60.627550] cryptsetup invoked oom-killer: gfp_mask=0x201da,
> order=0, oom_adj=0, oom_score_adj=0
> [ Â 60.627553] cryptsetup cpuset=/ mems_allowed=0
> [ Â 60.627555] Pid: 1910, comm: cryptsetup Not tainted 2.6.38.6-no-fpu+ #47
> [ Â 60.627556] Call Trace:
> [ Â 60.627563] Â[<ffffffff8107f9c5>] ? cpuset_print_task_mems_allowed+0x91/0x9c
> [ Â 60.627567] Â[<ffffffff810b3ef1>] ? dump_header+0x7f/0x1ba
> [ Â 60.627570] Â[<ffffffff8109e4d6>] ? trace_hardirqs_on+0x9/0x20
> [ Â 60.627572] Â[<ffffffff810b42ba>] ? oom_kill_process+0x50/0x24e
> [ Â 60.627574] Â[<ffffffff810b4961>] ? out_of_memory+0x2e4/0x359
> [ Â 60.627576] Â[<ffffffff810b879e>] ? __alloc_pages_nodemask+0x5f3/0x775
> [ Â 60.627579] Â[<ffffffff810e127e>] ? alloc_pages_current+0xbe/0xd8
> [ Â 60.627581] Â[<ffffffff810b2126>] ? __page_cache_alloc+0x77/0x7e
> [ Â 60.627585] Â[<ffffffff8135d009>] ? dm_table_unplug_all+0x52/0xed
> [ Â 60.627587] Â[<ffffffff810b9f74>] ? __do_page_cache_readahead+0x98/0x1a4
> [ Â 60.627589] Â[<ffffffff810ba321>] ? ra_submit+0x21/0x25
> [ Â 60.627590] Â[<ffffffff810ba4ee>] ? ondemand_readahead+0x1c9/0x1d8
> [ Â 60.627592] Â[<ffffffff810ba5dd>] ? page_cache_sync_readahead+0x3d/0x40
> [ Â 60.627594] Â[<ffffffff810b342d>] ? filemap_fault+0x119/0x36c
> [ Â 60.627597] Â[<ffffffff810caf5f>] ? __do_fault+0x56/0x342
> [ Â 60.627600] Â[<ffffffff810f5630>] ? lookup_page_cgroup+0x32/0x48
> [ Â 60.627602] Â[<ffffffff810cd437>] ? handle_pte_fault+0x29f/0x765
> [ Â 60.627604] Â[<ffffffff810ba75e>] ? add_page_to_lru_list+0x6e/0x73
> [ Â 60.627606] Â[<ffffffff810be487>] ? page_evictable+0x1b/0x8d
> [ Â 60.627607] Â[<ffffffff810bae36>] ? put_page+0x24/0x35
> [ Â 60.627610] Â[<ffffffff810cdbfc>] ? handle_mm_fault+0x18e/0x1a1
> [ Â 60.627612] Â[<ffffffff810cded2>] ? __get_user_pages+0x2c3/0x3ed
> [ Â 60.627614] Â[<ffffffff810cfb4b>] ? __mlock_vma_pages_range+0x67/0x6b
> [ Â 60.627616] Â[<ffffffff810cfc01>] ? do_mlock_pages+0xb2/0x11a
> [ Â 60.627618] Â[<ffffffff810d0448>] ? sys_mlockall+0x111/0x11c
> [ Â 60.627621] Â[<ffffffff81002a3b>] ? system_call_fastpath+0x16/0x1b
> [ Â 60.627623] Mem-Info:
> [ Â 60.627624] Node 0 DMA per-cpu:
> [ Â 60.627626] CPU Â Â0: hi: Â Â0, btch: Â 1 usd: Â 0
> [ Â 60.627627] CPU Â Â1: hi: Â Â0, btch: Â 1 usd: Â 0
> [ Â 60.627628] CPU Â Â2: hi: Â Â0, btch: Â 1 usd: Â 0
> [ Â 60.627629] CPU Â Â3: hi: Â Â0, btch: Â 1 usd: Â 0
> [ Â 60.627630] Node 0 DMA32 per-cpu:
> [ Â 60.627631] CPU Â Â0: hi: Â186, btch: Â31 usd: Â 0
> [ Â 60.627633] CPU Â Â1: hi: Â186, btch: Â31 usd: Â 0
> [ Â 60.627634] CPU Â Â2: hi: Â186, btch: Â31 usd: Â 0
> [ Â 60.627635] CPU Â Â3: hi: Â186, btch: Â31 usd: Â 0
> [ Â 60.627638] active_anon:51586 inactive_anon:17384 isolated_anon:0
> [ Â 60.627639] Âactive_file:0 inactive_file:226 isolated_file:0
> [ Â 60.627639] Âunevictable:395661 dirty:0 writeback:3 unstable:0
> [ Â 60.627640] Âfree:13258 slab_reclaimable:3979 slab_unreclaimable:9755
> [ Â 60.627640] Âmapped:11910 shmem:24046 pagetables:5062 bounce:0
> [ Â 60.627642] Node 0 DMA free:8352kB min:340kB low:424kB high:508kB
> active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:952kB
> unevictable:6580kB isolated(anon):0kB isolated(file):0kB
> present:15676kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB
> shmem:0kB slab_reclaimable:16kB slab_unreclaimable:0kB
> kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB
> writeback_tmp:0kB pages_scanned:1645 all_unreclaimable? yes
> [ Â 60.627649] lowmem_reserve[]: 0 2004 2004 2004
> [ Â 60.627651] Node 0 DMA32 free:44680kB min:44712kB low:55888kB
> high:67068kB active_anon:206344kB inactive_anon:69536kB
> active_file:0kB inactive_file:0kB unevictable:1576064kB
> isolated(anon):0kB isolated(file):0kB present:2052320kB
> mlocked:47540kB dirty:0kB writeback:12kB mapped:47640kB shmem:96184kB
> slab_reclaimable:15900kB slab_unreclaimable:39020kB
> kernel_stack:2424kB pagetables:20248kB unstable:0kB bounce:0kB
> writeback_tmp:0kB pages_scanned:499225 all_unreclaimable? yes
> [ Â 60.627658] lowmem_reserve[]: 0 0 0 0
> [ Â 60.627660] Node 0 DMA: 0*4kB 0*8kB 2*16kB 2*32kB 1*64kB 2*128kB
> 1*256kB 1*512kB 1*1024kB 3*2048kB 0*4096kB = 8352kB
> [ Â 60.627665] Node 0 DMA32: 959*4kB 2071*8kB 682*16kB 165*32kB
> 27*64kB 4*128kB 0*256kB 0*512kB 0*1024kB 1*2048kB 1*4096kB = 44980kB
> [ Â 60.627670] 419957 total pagecache pages
> [ Â 60.627671] 0 pages in swap cache
> [ Â 60.627672] Swap cache stats: add 137, delete 137, find 0/0
> [ Â 60.627673] Free swap Â= 6290904kB
> [ Â 60.627674] Total swap = 6291452kB
> [ Â 60.632560] 524272 pages RAM
> [ Â 60.632562] 9451 pages reserved
> [ Â 60.632563] 45558 pages shared
> [ Â 60.632564] 469944 pages non-shared
>
>
> There are about 270M anon Âand lots of free swap space in system.
> Nonetheless, he saw the OOM. I think it doesn't make sense.
> As I look above log, he used swap as crypted device mapper and used 1.4G ramfs.
> Andy, Right?
>
> The thing I doubt firstly was a big ramfs.
> I think in reclaim, shrink_page_list will start to cull mlocked page.
> If there are so many ramfs pages and working set pages in LRU,
> reclaimer can't reclaim any page until It meet non-unevictable pages
> or non-working set page(!PG_referenced and !pte_young). His workload
> had lots of anon pages and ramfs pages. ramfs pages is unevictable
> page so that it would cull and anon pages are promoted very easily so
> that we can't reclaim it easily.
> It means zone->pages_scanned would be very high so after all,
> zone->all_unreclaimable would set.
> As I look above log, the number of lru in ÂDMA32 zone is 68970.
> The number of unevictable page is 394016.
>
> 394016 + working set page(I don't know) is almost equal to Â(68970 * 6
> = 413820).
> So it's possible that zone->all_unreclaimable is set.
> I wanted to test below patch by private but it doesn't solve his problem.
> But I think we need below patch, still. It can happen if we had lots
> of LRU order successive mlocked page in LRU.
>
> ===
>
> From e37f150328aedeea9a88b6190ab2b6e6c1067163 Mon Sep 17 00:00:00 2001
> From: Minchan Kim <minchan.kim@xxxxxxxxx>
> Date: Wed, 25 May 2011 07:09:17 +0900
> Subject: [PATCH 3/3] vmscan: decrease pages_scanned on unevictable page
>
> If there are many unevictable pages on evictable LRU list(ex, big ramfs),
> shrink_page_list will move it into unevictable and can't reclaim pages.
> But we already increased zone->pages_scanned.
> If the situation is repeated, the number of evictable lru pages is decreased
> while zone->pages_scanned is increased without reclaim any pages.
> It could turn on zone->all_unreclaimable but it's totally false alram.
>
> Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
> ---
> Âmm/vmscan.c | Â 22 +++++++++++++++++++---
> Â1 files changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 08d3077..a7df813 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -700,7 +700,8 @@ static noinline_for_stack void
> free_page_list(struct list_head *free_pages)
> Âstatic unsigned long shrink_page_list(struct list_head *page_list,
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Âstruct zone *zone,
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Âstruct scan_control *sc,
> - Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â unsigned long *dirty_pages)
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â unsigned long *dirty_pages,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â unsigned long *unevictable_pages)
> Â{
> Â Â Â ÂLIST_HEAD(ret_pages);
> Â Â Â ÂLIST_HEAD(free_pages);
> @@ -708,6 +709,7 @@ static unsigned long shrink_page_list(struct
> list_head *page_list,
> Â Â Â Âunsigned long nr_dirty = 0;
> Â Â Â Âunsigned long nr_congested = 0;
> Â Â Â Âunsigned long nr_reclaimed = 0;
> + Â Â Â unsigned long nr_unevictable = 0;
>
> Â Â Â Âcond_resched();
>
> @@ -908,6 +910,7 @@ cull_mlocked:
> Â Â Â Â Â Â Â Â Â Â Â Âtry_to_free_swap(page);
> Â Â Â Â Â Â Â Âunlock_page(page);
> Â Â Â Â Â Â Â Âputback_lru_page(page);
> + Â Â Â Â Â Â Â nr_unevictable++;
> Â Â Â Â Â Â Â Âcontinue;
>
> Âactivate_locked:
> @@ -936,6 +939,7 @@ keep_lumpy:
> Â Â Â Â Â Â Â Âzone_set_flag(zone, ZONE_CONGESTED);
>
> Â Â Â Â*dirty_pages = nr_dirty;
> + Â Â Â *unevictable_pages = nr_unevictable;
> Â Â Â Âfree_page_list(&free_pages);
>
> Â Â Â Âlist_splice(&ret_pages, page_list);
> @@ -1372,6 +1376,7 @@ shrink_inactive_list(unsigned long nr_to_scan,
> struct zone *zone,
> Â Â Â Âunsigned long nr_scanned;
> Â Â Â Âunsigned long nr_reclaimed = 0;
> Â Â Â Âunsigned long nr_dirty;
> + Â Â Â unsigned long nr_unevictable;
> Â Â Â Âunsigned long nr_taken;
> Â Â Â Âunsigned long nr_anon;
> Â Â Â Âunsigned long nr_file;
> @@ -1425,7 +1430,7 @@ shrink_inactive_list(unsigned long nr_to_scan,
> struct zone *zone,
> Â Â Â Âspin_unlock_irq(&zone->lru_lock);
>
> Â Â Â Âreclaim_mode = sc->reclaim_mode;
> - Â Â Â nr_reclaimed = shrink_page_list(&page_list, zone, sc, &nr_dirty);
> + Â Â Â nr_reclaimed = shrink_page_list(&page_list, zone, sc, &nr_dirty,
> &nr_unevictable);
>
> Â Â Â Â/* Check if we should syncronously wait for writeback */
> Â Â Â Âif ((nr_dirty && !(reclaim_mode & RECLAIM_MODE_SINGLE) &&
> @@ -1434,7 +1439,8 @@ shrink_inactive_list(unsigned long nr_to_scan,
> struct zone *zone,
> Â Â Â Â Â Â Â Âunsigned long nr_active = clear_active_flags(&page_list, NULL);
> Â Â Â Â Â Â Â Âcount_vm_events(PGDEACTIVATE, nr_active);
> Â Â Â Â Â Â Â Âset_reclaim_mode(priority, sc, true);
> - Â Â Â Â Â Â Â nr_reclaimed += shrink_page_list(&page_list, zone, sc, &nr_dirty);
> + Â Â Â Â Â Â Â nr_reclaimed += shrink_page_list(&page_list, zone, sc,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â &nr_dirty, &nr_unevictable);
> Â Â Â Â}
>
> Â Â Â Âlocal_irq_disable();
> @@ -1442,6 +1448,16 @@ shrink_inactive_list(unsigned long nr_to_scan,
> struct zone *zone,
> Â Â Â Â Â Â Â Â__count_vm_events(KSWAPD_STEAL, nr_reclaimed);
> Â Â Â Â__count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
>
> + Â Â Â /*
> + Â Â Â Â* Too many unevictalbe pages on evictable LRU list(ex, big ramfs)
> + Â Â Â Â* can make high zone->pages_scanned and reduce the number of lru page
> + Â Â Â Â* on evictable lru as reclaim is going on.
> + Â Â Â Â* It could turn on all_unreclaimable which is false alarm.
> + Â Â Â Â*/
> + Â Â Â spin_lock(&zone->lru_lock);
> + Â Â Â if (zone->pages_scanned >= nr_unevictable)
> + Â Â Â Â Â Â Â zone->pages_scanned -= nr_unevictable;
> + Â Â Â else
> + Â Â Â Â Â Â Â zone->pages_scanned = 0;
> + Â Â Â spin_unlock(&zone->lru_lock);
> +
> Â Â Â Âputback_lru_pages(zone, sc, nr_anon, nr_file, &page_list);
>
> Â Â Â Âtrace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
> --
> 1.7.1
>
> ===
>
> Then, what I doubt secondly is zone_set_flag(zone, ZONE_CONGESTED).
> He used swap as crypted device mapper.
> Device mapper could make IO slow for his work. It means we are likely
> to meet ZONE_CONGESTED higher than normal swap.
>
> Let's think about it.
> Swap device is very congested so shrink_page_list would set the zone
> as CONGESTED.
> Who is clear ZONE_CONGESTED? There are two place in Âkswapd.
> One work in only order > 0. So maybe, it's no-op in Andy's
> workload.(ie, it's mostly order-0 allocation)
> One remained is below.
>
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â * If a zone reaches its high watermark,
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â * consider it to be no longer congested. It's
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â * possible there are dirty pages backed by
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â * congested BDIs but as pressure is relieved,
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â * spectulatively avoid congestion waits
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â */
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Âzone_clear_flag(zone, ZONE_CONGESTED);
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Âif (i <= *classzone_idx)
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Âbalanced += zone->present_pages;
>
> It works only if the zone meets high watermark. If allocation is
> faster than reclaim(ie, it's true for slow swap device), the zone
> would remain congested.
> It means swapout would block.
> As we see the OOM log, we can know that DMA32 zone can't meet high watermark.
>
> Does my guessing make sense?
Hi Andrew.
I got failed your scenario in my machine so could you be willing to
test this patch for proving my above scenario?
The patch is just revert patch of 0e093d99[do not sleep on the
congestion queue...] for 2.6.38.6.
I would like to test it for proving my above zone congestion scenario.
I did it based on 2.6.38.6 for your easy apply so you must apply it
cleanly on vanilla v2.6.38.6.
And you have to add !pgdat_balanced and shrink_slab patch.
Thanks, Andrew.
--
Kind regards,
Minchan Kim
From 244e37f1f3978ff182b5e33b77b327e4f48bb438 Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan.kim@xxxxxxxxx>
Date: Mon, 30 May 2011 02:23:49 +0900
Subject: [PATCH] Revert "writeback: do not sleep on the congestion queue if there are no congested BDIs or if significant congestion is not being encountered in the current zone"
This reverts commit 0e093d99763eb4cea09f8ca4f1d01f34e121d10b.
Conflicts:
mm/vmscan.c
Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
---
include/linux/backing-dev.h | 2 +-
include/linux/mmzone.h | 8 -----
include/trace/events/writeback.h | 7 ----
mm/backing-dev.c | 61 +------------------------------------
mm/page_alloc.c | 4 +-
mm/vmscan.c | 41 ++-----------------------
6 files changed, 9 insertions(+), 114 deletions(-)
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 4ce34fa..8b0ae8b 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -286,7 +286,7 @@ enum {
void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
void set_bdi_congested(struct backing_dev_info *bdi, int sync);
long congestion_wait(int sync, long timeout);
-long wait_iff_congested(struct zone *zone, int sync, long timeout);
+
static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
{
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 02ecb01..e1b16aa 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -424,9 +424,6 @@ struct zone {
typedef enum {
ZONE_RECLAIM_LOCKED, /* prevents concurrent reclaim */
ZONE_OOM_LOCKED, /* zone is in OOM killer zonelist */
- ZONE_CONGESTED, /* zone has many dirty pages backed by
- * a congested BDI
- */
} zone_flags_t;
static inline void zone_set_flag(struct zone *zone, zone_flags_t flag)
@@ -444,11 +441,6 @@ static inline void zone_clear_flag(struct zone *zone, zone_flags_t flag)
clear_bit(flag, &zone->flags);
}
-static inline int zone_is_reclaim_congested(const struct zone *zone)
-{
- return test_bit(ZONE_CONGESTED, &zone->flags);
-}
-
static inline int zone_is_reclaim_locked(const struct zone *zone)
{
return test_bit(ZONE_RECLAIM_LOCKED, &zone->flags);
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 4e249b9..fc2b3a0 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -180,13 +180,6 @@ DEFINE_EVENT(writeback_congest_waited_template, writeback_congestion_wait,
TP_ARGS(usec_timeout, usec_delayed)
);
-DEFINE_EVENT(writeback_congest_waited_template, writeback_wait_iff_congested,
-
- TP_PROTO(unsigned int usec_timeout, unsigned int usec_delayed),
-
- TP_ARGS(usec_timeout, usec_delayed)
-);
-
#endif /* _TRACE_WRITEBACK_H */
/* This part must be outside protection */
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 8e4ed88..c9e59de 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -729,7 +729,6 @@ static wait_queue_head_t congestion_wqh[2] = {
__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
};
-static atomic_t nr_bdi_congested[2];
void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
{
@@ -737,8 +736,7 @@ void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
wait_queue_head_t *wqh = &congestion_wqh[sync];
bit = sync ? BDI_sync_congested : BDI_async_congested;
- if (test_and_clear_bit(bit, &bdi->state))
- atomic_dec(&nr_bdi_congested[sync]);
+ clear_bit(bit, &bdi->state);
smp_mb__after_clear_bit();
if (waitqueue_active(wqh))
wake_up(wqh);
@@ -750,8 +748,7 @@ void set_bdi_congested(struct backing_dev_info *bdi, int sync)
enum bdi_state bit;
bit = sync ? BDI_sync_congested : BDI_async_congested;
- if (!test_and_set_bit(bit, &bdi->state))
- atomic_inc(&nr_bdi_congested[sync]);
+ set_bit(bit, &bdi->state);
}
EXPORT_SYMBOL(set_bdi_congested);
@@ -782,57 +779,3 @@ long congestion_wait(int sync, long timeout)
}
EXPORT_SYMBOL(congestion_wait);
-/**
- * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes
- * @zone: A zone to check if it is heavily congested
- * @sync: SYNC or ASYNC IO
- * @timeout: timeout in jiffies
- *
- * In the event of a congested backing_dev (any backing_dev) and the given
- * @zone has experienced recent congestion, this waits for up to @timeout
- * jiffies for either a BDI to exit congestion of the given @sync queue
- * or a write to complete.
- *
- * In the absense of zone congestion, cond_resched() is called to yield
- * the processor if necessary but otherwise does not sleep.
- *
- * The return value is 0 if the sleep is for the full timeout. Otherwise,
- * it is the number of jiffies that were still remaining when the function
- * returned. return_value == timeout implies the function did not sleep.
- */
-long wait_iff_congested(struct zone *zone, int sync, long timeout)
-{
- long ret;
- unsigned long start = jiffies;
- DEFINE_WAIT(wait);
- wait_queue_head_t *wqh = &congestion_wqh[sync];
-
- /*
- * If there is no congestion, or heavy congestion is not being
- * encountered in the current zone, yield if necessary instead
- * of sleeping on the congestion queue
- */
- if (atomic_read(&nr_bdi_congested[sync]) == 0 ||
- !zone_is_reclaim_congested(zone)) {
- cond_resched();
-
- /* In case we scheduled, work out time remaining */
- ret = timeout - (jiffies - start);
- if (ret < 0)
- ret = 0;
-
- goto out;
- }
-
- /* Sleep until uncongested or a write happens */
- prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
- ret = io_schedule_timeout(timeout);
- finish_wait(wqh, &wait);
-
-out:
- trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
- jiffies_to_usecs(jiffies - start));
-
- return ret;
-}
-EXPORT_SYMBOL(wait_iff_congested);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2828037..71e9842 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1929,7 +1929,7 @@ __alloc_pages_high_priority(gfp_t gfp_mask, unsigned int order,
preferred_zone, migratetype);
if (!page && gfp_mask & __GFP_NOFAIL)
- wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/50);
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
} while (!page && (gfp_mask & __GFP_NOFAIL));
return page;
@@ -2137,7 +2137,7 @@ rebalance:
pages_reclaimed += did_some_progress;
if (should_alloc_retry(gfp_mask, order, pages_reclaimed)) {
/* Wait for some write requests to complete then retry */
- wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/50);
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
goto rebalance;
} else {
/*
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 0665520..59de427 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -703,14 +703,11 @@ static noinline_for_stack void free_page_list(struct list_head *free_pages)
* shrink_page_list() returns the number of reclaimed pages
*/
static unsigned long shrink_page_list(struct list_head *page_list,
- struct zone *zone,
struct scan_control *sc)
{
LIST_HEAD(ret_pages);
LIST_HEAD(free_pages);
int pgactivate = 0;
- unsigned long nr_dirty = 0;
- unsigned long nr_congested = 0;
unsigned long nr_reclaimed = 0;
cond_resched();
@@ -730,7 +727,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
goto keep;
VM_BUG_ON(PageActive(page));
- VM_BUG_ON(page_zone(page) != zone);
sc->nr_scanned++;
@@ -808,8 +804,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
}
if (PageDirty(page)) {
- nr_dirty++;
-
if (references == PAGEREF_RECLAIM_CLEAN)
goto keep_locked;
if (!may_enter_fs)
@@ -820,7 +814,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
/* Page is dirty, try to write it out here */
switch (pageout(page, mapping, sc)) {
case PAGE_KEEP:
- nr_congested++;
goto keep_locked;
case PAGE_ACTIVATE:
goto activate_locked;
@@ -931,15 +924,6 @@ keep_lumpy:
VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
}
- /*
- * Tag a zone as congested if all the dirty pages encountered were
- * backed by a congested BDI. In this case, reclaimers should just
- * back off and wait for congestion to clear because further reclaim
- * will encounter the same problem
- */
- if (nr_dirty == nr_congested && nr_dirty != 0)
- zone_set_flag(zone, ZONE_CONGESTED);
-
free_page_list(&free_pages);
list_splice(&ret_pages, page_list);
@@ -1426,12 +1410,12 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
spin_unlock_irq(&zone->lru_lock);
- nr_reclaimed = shrink_page_list(&page_list, zone, sc);
+ nr_reclaimed = shrink_page_list(&page_list, sc);
/* Check if we should syncronously wait for writeback */
if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
set_reclaim_mode(priority, sc, true);
- nr_reclaimed += shrink_page_list(&page_list, zone, sc);
+ nr_reclaimed += shrink_page_list(&page_list, sc);
}
local_irq_disable();
@@ -2085,14 +2069,8 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
/* Take a nap, wait for some writeback to complete */
if (!sc->hibernation_mode && sc->nr_scanned &&
- priority < DEF_PRIORITY - 2) {
- struct zone *preferred_zone;
-
- first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask),
- &cpuset_current_mems_allowed,
- &preferred_zone);
- wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10);
- }
+ priority < DEF_PRIORITY - 2)
+ congestion_wait(BLK_RW_ASYNC, HZ/10);
}
out:
@@ -2455,14 +2433,6 @@ loop_again:
min_wmark_pages(zone), end_zone, 0))
has_under_min_watermark_zone = 1;
} else {
- /*
- * If a zone reaches its high watermark,
- * consider it to be no longer congested. It's
- * possible there are dirty pages backed by
- * congested BDIs but as pressure is relieved,
- * spectulatively avoid congestion waits
- */
- zone_clear_flag(zone, ZONE_CONGESTED);
if (i <= *classzone_idx)
balanced += zone->present_pages;
}
@@ -2546,9 +2516,6 @@ out:
order = sc.order = 0;
goto loop_again;
}
-
- /* If balanced, clear the congested flag */
- zone_clear_flag(zone, ZONE_CONGESTED);
}
}
--
1.7.0.4