Linux-mm Archive on lore.kernel.org
 help / color / Atom feed
From: Qian Cai <cai@redhat.com>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>, linux-mm@kvack.org
Cc: intel-gfx@lists.freedesktop.org,
	Huang Ying <ying.huang@intel.com>,
	Hugh Dickins <hughd@google.com>,
	linux-kernel@vger.kernel.org,
	Chris Wilson <chris@chris-wilson.co.uk>,
	 William Kucharski <william.kucharski@oracle.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	cgroups@vger.kernel.org,
	 Andrew Morton <akpm@linux-foundation.org>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Matthew Auld <matthew.auld@intel.com>
Subject: Re: [PATCH v2 3/8] mm: Optimise madvise WILLNEED
Date: Mon, 14 Sep 2020 12:47:26 -0400
Message-ID: <54766b04a5bc21b8573666b0c4b50b3e982ed5e5.camel@redhat.com> (raw)
In-Reply-To: <c48c5eaa09d1ea5b78b12b545c034d1e937c49ba.camel@redhat.com>

On Mon, 2020-09-14 at 12:17 -0400, Qian Cai wrote:
> On Thu, 2020-09-10 at 19:33 +0100, Matthew Wilcox (Oracle) wrote:
> > Instead of calling find_get_entry() for every page index, use an XArray
> > iterator to skip over NULL entries, and avoid calling get_page(),
> > because we only want the swap entries.
> > 
> > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> > Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> 
> Reverting the "Return head pages from find_*_entry" patchset [1] up to this
> patch fixed the issue that LTP madvise06 test [2] would trigger endless soft-
> lockups below. It does not help after applied patches fixed other separate
> issues in the patchset [3][4].

Forgot to send this piece of RCU stall traces as well which might help
debugging.

00: [ 2852.137748] madvise06 (62712): drop_caches: 3                            
01: [ 2928.208367] rcu: INFO: rcu_sched self-detected stall on CPU              
01: [ 2928.210083] rcu:     1-....: (6499 ticks this GP) idle=036/1/0x4000000000
01: 000002 softirq=1741392/1741392 fqs=3161                                     
01: [ 2928.210610]  (t=6500 jiffies g=610849 q=12529)                           
01: [ 2928.210620] Task dump for CPU 1:                                         
01: [ 2928.210630] task:madvise06       state:R  running task     stack:53320 pi
01: d:62712 ppid: 62711 flags:0x00000004                                        
01: [ 2928.210676] Call Trace:                                                  
01: [ 2928.210693]  [<00000000af57ec88>] show_stack+0x158/0x1f0                 
01: [ 2928.210703]  [<00000000ae55b692>] sched_show_task+0x3d2/0x4c8            
01: [ 2928.210710]  [<00000000af5846aa>] rcu_dump_cpu_stacks+0x26a/0x2a8        
01: [ 2928.210718]  [<00000000ae64fa62>] rcu_sched_clock_irq+0x1c92/0x2188      
01: [ 2928.210726]  [<00000000ae6662ee>] update_process_times+0x4e/0x148        
01: [ 2928.210734]  [<00000000ae690c26>] tick_sched_timer+0x86/0x188            
01: [ 2928.210741]  [<00000000ae66989c>] __hrtimer_run_queues+0x84c/0x10b8      
01: [ 2928.210748]  [<00000000ae66c80a>] hrtimer_interrupt+0x38a/0x860          
01: [ 2928.210758]  [<00000000ae48dbf2>] do_IRQ+0x152/0x1c8                     
01: [ 2928.210767]  [<00000000af5b00ea>] ext_int_handler+0x18e/0x194            
01: [ 2928.210774]  [<00000000ae5e332e>] arch_local_irq_restore+0x86/0xa0       
01: [ 2928.210782]  [<00000000af58da04>] lock_is_held_type+0xe4/0x130           
01: [ 2928.210791]  [<00000000ae63355a>] rcu_read_lock_held+0xba/0xd8           
01: [ 2928.210799]  [<00000000af0125fc>] xas_descend+0x244/0x2c8                
01: [ 2928.210806]  [<00000000af012754>] xas_load+0xd4/0x148                    
01: [ 2928.210812]  [<00000000af014490>] xas_find+0x5d0/0x818                   
01: [ 2928.210822]  [<00000000ae97e644>] do_madvise+0xd5c/0x1600                
01: [ 2928.210828]  [<00000000ae97f2d2>] __s390x_sys_madvise+0x72/0x98          
01: [ 2928.210835]  [<00000000af5af844>] system_call+0xdc/0x278                 
01: [ 2928.210841] 3 locks held by madvise06/62712:                             
01: [ 2928.216406]  #0: 00000001437fca18 (&mm->mmap_lock){++++}-{3:3}, at: do_m 
01: dvise+0x18c/0x1600                                                          
01: [ 2928.216430]  #1: 00000000afbdd3e0 (rcu_read_lock){....}-{1:2}, at: do_mad
01: vise+0xe72/0x1600                                                           
01: [ 2928.216449]  #2: 00000000afbe0818 (rcu_node_1){-.-.}-{2:2}, at: rcu_dump_
01: cpu_stacks+0xb2/0x2a8



  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-10 18:33 [PATCH v2 0/8] Return head pages from find_*_entry Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 1/8] mm: Factor find_get_incore_page out of mincore_page Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 2/8] mm: Use find_get_incore_page in memcontrol Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 3/8] mm: Optimise madvise WILLNEED Matthew Wilcox (Oracle)
2020-09-14 16:17   ` Qian Cai
2020-09-14 16:47     ` Qian Cai [this message]
2020-09-14 16:50     ` Matthew Wilcox
2020-09-14 19:44       ` Qian Cai
2020-09-10 18:33 ` [PATCH v2 4/8] proc: Optimise smaps for shmem entries Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 5/8] i915: Use find_lock_page instead of find_lock_entry Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 6/8] mm: Convert find_get_entry to return the head page Matthew Wilcox (Oracle)
2020-09-14  8:55   ` [mm] 2037ab69a5: BUG:KASAN:null-ptr-deref_in_t kernel test robot
2020-09-14 11:27     ` Matthew Wilcox
2020-09-10 18:33 ` [PATCH v2 7/8] mm/shmem: Return head page from find_lock_entry Matthew Wilcox (Oracle)
2020-09-12  3:20   ` Matthew Wilcox
2020-09-10 18:33 ` [PATCH v2 8/8] mm: Add find_lock_head Matthew Wilcox (Oracle)
2020-09-15  8:10 ` [PATCH v2 0/8] Return head pages from find_*_entry Hugh Dickins
2020-09-15 12:53   ` Naresh Kamboju
2020-09-15 13:08     ` Matthew Wilcox

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=54766b04a5bc21b8573666b0c4b50b3e982ed5e5.camel@redhat.com \
    --to=cai@redhat.com \
    --cc=adobriyan@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=cgroups@vger.kernel.org \
    --cc=chris@chris-wilson.co.uk \
    --cc=hannes@cmpxchg.org \
    --cc=hughd@google.com \
    --cc=intel-gfx@lists.freedesktop.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=matthew.auld@intel.com \
    --cc=william.kucharski@oracle.com \
    --cc=willy@infradead.org \
    --cc=ying.huang@intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-mm Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-mm/0 linux-mm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-mm linux-mm/ https://lore.kernel.org/linux-mm \
		linux-mm@kvack.org
	public-inbox-index linux-mm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kvack.linux-mm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git