linux-kernel - Re: [PATCH][v2] PM / Hibernate: Feed the wathdog when creating snapshot

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Message-ID: <20170823034439.GA29634@yu-desktop-1.sh.intel.com>
Date:   Wed, 23 Aug 2017 11:44:39 +0800
From:   Chen Yu <yu.c.chen@...el.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Vlastimil Babka <vbabka@...e.cz>, Len Brown <lenb@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][v2] PM / Hibernate: Feed the wathdog when creating
 snapshot

On Tue, Aug 22, 2017 at 02:55:39PM +0200, Rafael J. Wysocki wrote:
> On Tuesday, August 22, 2017 5:20:02 AM CEST Chen Yu wrote:
> > There is a problem that when counting the pages for creating
> > the hibernation snapshot will take significant amount of
> > time, especially on system with large memory. Since the counting
> > job is performed with irq disabled, this might lead to NMI lockup.
> > The following warning were found on a system with 1.5TB DRAM:
> > 
> > [ 1124.758184] Freezing user space processes ... (elapsed 0.002 seconds) done.
> > [ 1124.768721] OOM killer disabled.
> > [ 1124.847009] PM: Preallocating image memory...
> > [ 1139.392042] NMI watchdog: Watchdog detected hard LOCKUP on cpu 27
> > [ 1139.392076] CPU: 27 PID: 3128 Comm: systemd-sleep Not tainted 4.13.0-0.rc2.git0.1.fc27.x86_64 #1
> > [ 1139.392077] task: ffff9f01971ac000 task.stack: ffffb1a3f325c000
> > [ 1139.392083] RIP: 0010:memory_bm_find_bit+0xf4/0x100
> > [ 1139.392084] RSP: 0018:ffffb1a3f325fc20 EFLAGS: 00000006
> > [ 1139.392084] RAX: 0000000000000000 RBX: 0000000013b83000 RCX: ffff9fbe89caf000
> > [ 1139.392085] RDX: ffffb1a3f325fc30 RSI: 0000000000003200 RDI: ffff9fbeaffffe80
> > [ 1139.392085] RBP: ffffb1a3f325fc40 R08: 0000000013b80000 R09: ffff9fbe89c54878
> > [ 1139.392085] R10: ffffb1a3f325fc2c R11: 0000000013b83200 R12: 0000000000000400
> > [ 1139.392086] R13: fffffd552e0c0000 R14: ffff9fc1bffd31e0 R15: 0000000000000202
> > [ 1139.392086] FS:  00007f3189704180(0000) GS:ffff9fbec8ec0000(0000) knlGS:0000000000000000
> > [ 1139.392087] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [ 1139.392087] CR2: 00000085da0f7398 CR3: 000001771cf9a000 CR4: 00000000007406e0
> > [ 1139.392088] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > [ 1139.392088] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > [ 1139.392088] PKRU: 55555554
> > [ 1139.392089] Call Trace:
> > [ 1139.392092]  ? memory_bm_set_bit+0x29/0x60
> > [ 1139.392094]  swsusp_set_page_free+0x2b/0x30
> > [ 1139.392098]  mark_free_pages+0x147/0x1c0
> > [ 1139.392099]  count_data_pages+0x41/0xa0
> > [ 1139.392101]  hibernate_preallocate_memory+0x80/0x450
> > [ 1139.392102]  hibernation_snapshot+0x58/0x410
> > [ 1139.392103]  hibernate+0x17c/0x310
> > [ 1139.392104]  state_store+0xdf/0xf0
> > [ 1139.392107]  kobj_attr_store+0xf/0x20
> > [ 1139.392111]  sysfs_kf_write+0x37/0x40
> > [ 1139.392113]  kernfs_fop_write+0x11c/0x1a0
> > [ 1139.392117]  __vfs_write+0x37/0x170
> > [ 1139.392121]  ? handle_mm_fault+0xd8/0x230
> > [ 1139.392122]  vfs_write+0xb1/0x1a0
> > [ 1139.392123]  SyS_write+0x55/0xc0
> > [ 1139.392126]  entry_SYSCALL_64_fastpath+0x1a/0xa5
> > ...
> > [ 1144.690405] done (allocated 6590003 pages)
> > [ 1144.694971] PM: Allocated 26360012 kbytes in 19.89 seconds (1325.28 MB/s)
> > 
> > It has taken nearly 20 seconds(2.10GHz CPU) thus the NMI lockup
> > was triggered. In case the timeout of the NMI watch dog has been
> > set to 1 second, a safe interval should be 6590003/20 = 320k pages
> > in theory. However there might also be some platforms running at a
> > lower frequency, so feed the watchdog every 128k pages(per Andrew's
> > suggestion, this should avoid the modulus operation).
> > 
> > Reported-by: Jan Filipcewicz <jan.filipcewicz@...el.com>
> > Suggested-by: Michal Hocko <mhocko@...e.com>
> > Reviewed-by: Michal Hocko <mhocko@...e.com>
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > Cc: Michal Hocko <mhocko@...nel.org>
> > Cc: Mel Gorman <mgorman@...hsingularity.net>
> > Cc: Vlastimil Babka <vbabka@...e.cz>
> > Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> > Cc: Len Brown <lenb@...nel.org>
> > Cc: Dan Williams <dan.j.williams@...el.com>
> > Cc: linux-pm@...r.kernel.org
> > Cc: linux-kernel@...r.kernel.org
> > Signed-off-by: Chen Yu <yu.c.chen@...el.com>
> > ---
> > v2: Use an interval of 128k instead of 100k to
> >     avoid the modulus operation.
> > --
> >  mm/page_alloc.c | 17 +++++++++++++++--
> >  1 file changed, 15 insertions(+), 2 deletions(-)
> > 
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 1bad301..3cf4201 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -66,6 +66,7 @@
> >  #include <linux/kthread.h>
> >  #include <linux/memcontrol.h>
> >  #include <linux/ftrace.h>
> > +#include <linux/nmi.h>
> >  
> >  #include <asm/sections.h>
> >  #include <asm/tlbflush.h>
> > @@ -2535,9 +2536,15 @@ void drain_all_pages(struct zone *zone)
> >  
> >  #ifdef CONFIG_HIBERNATION
> >  
> > +/*
> > + * Touch the watchdog for every WD_INTERVAL_PAGE pages,
> > + * choose a power of 2 to avoid the modulus operation.
> > + */
> > +#define WD_INTERVAL_PAGE	(128*1024)
> 
> Sort of on a second thought I would define
> 
> #define WD_PAGE_COUNT		(128*1024)
> 
> and then ->
> 
> > +
> >  void mark_free_pages(struct zone *zone)
> >  {
> > -	unsigned long pfn, max_zone_pfn;
> > +	unsigned long pfn, max_zone_pfn, page_num = 0;
> 
> +	unsigned long pfn, max_zone_pfn, page_count = WD_PAGE_COUNT;
> 
> >  	unsigned long flags;
> >  	unsigned int order, t;
> >  	struct page *page;
> > @@ -2552,6 +2559,9 @@ void mark_free_pages(struct zone *zone)
> >  		if (pfn_valid(pfn)) {
> >  			page = pfn_to_page(pfn);
> >  
> > +			if (!((page_num++) % WD_INTERVAL_PAGE))
> > +				touch_nmi_watchdog();
> > +
> 
> ->
> 
> 	if (!--page_count) {
> 		touch_nmi_watchdog();
> 		page_count = WD_PAGE_COUNT;
> 	}
>
I guess this is to avoid the possible overflow if the page number is too large?
I'll send another version out.

Thanks,
	Yu