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[37.188.180.223]) by smtp.gmail.com with ESMTPSA id a2sm12141202wrp.13.2020.04.03.07.12.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Apr 2020 07:12:29 -0700 (PDT) Date: Fri, 3 Apr 2020 16:12:28 +0200 From: Michal Hocko To: Pavel Tatashin Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, dan.j.williams@intel.com, shile.zhang@linux.alibaba.com, daniel.m.jordan@oracle.com, ktkhai@virtuozzo.com, david@redhat.com, jmorris@namei.org, sashal@kernel.org, vbabka@suse.cz Subject: Re: [PATCH v4 3/3] mm: call cond_resched() from deferred_init_memmap() Message-ID: <20200403141228.GF22681@dhcp22.suse.cz> References: <20200403140952.17177-1-pasha.tatashin@soleen.com> <20200403140952.17177-4-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200403140952.17177-4-pasha.tatashin@soleen.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 03-04-20 10:09:52, Pavel Tatashin wrote: > Now that deferred pages are initialized with interrupts enabled we can > replace touch_nmi_watchdog() with cond_resched(), as it was before > 3a2d7fa8a3d5. > > For now, we cannot do the same in deferred_grow_zone() as it is still > initializes pages with interrupts disabled. > > This change fixes RCU problem described: > linux-mm/20200401104156.11564-2-david@redhat.com > > [ 60.474005] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: > [ 60.475000] rcu: 1-...0: (0 ticks this GP) idle=02a/1/0x4000000000000000 softirq=1/1 fqs=15000 > [ 60.475000] rcu: (detected by 0, t=60002 jiffies, g=-1199, q=1) > [ 60.475000] Sending NMI from CPU 0 to CPUs 1: > [ 1.760091] NMI backtrace for cpu 1 > [ 1.760091] CPU: 1 PID: 20 Comm: pgdatinit0 Not tainted 4.18.0-147.9.1.el8_1.x86_64 #1 > [ 1.760091] Hardware name: Red Hat KVM, BIOS 1.13.0-1.module+el8.2.0+5520+4e5817f3 04/01/2014 > [ 1.760091] RIP: 0010:__init_single_page.isra.65+0x10/0x4f > [ 1.760091] Code: 48 83 cf 63 48 89 f8 0f 1f 40 00 48 89 c6 48 89 d7 e8 6b 18 80 ff 66 90 5b c3 31 c0 b9 10 00 00 00 49 89 f8 48 c1 e6 33 f3 ab 07 00 00 00 48 c1 e2 36 41 c7 40 34 01 00 00 00 48 c1 e0 33 41 > [ 1.760091] RSP: 0000:ffffba783123be40 EFLAGS: 00000006 > [ 1.760091] RAX: 0000000000000000 RBX: fffffad34405e300 RCX: 0000000000000000 > [ 1.760091] RDX: 0000000000000000 RSI: 0010000000000000 RDI: fffffad34405e340 > [ 1.760091] RBP: 0000000033f3177e R08: fffffad34405e300 R09: 0000000000000002 > [ 1.760091] R10: 000000000000002b R11: ffff98afb691a500 R12: 0000000000000002 > [ 1.760091] R13: 0000000000000000 R14: 000000003f03ea00 R15: 000000003e10178c > [ 1.760091] FS: 0000000000000000(0000) GS:ffff9c9ebeb00000(0000) knlGS:0000000000000000 > [ 1.760091] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 1.760091] CR2: 00000000ffffffff CR3: 000000a1cf20a001 CR4: 00000000003606e0 > [ 1.760091] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 1.760091] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 1.760091] Call Trace: > [ 1.760091] deferred_init_pages+0x8f/0xbf > [ 1.760091] deferred_init_memmap+0x184/0x29d > [ 1.760091] ? deferred_free_pages.isra.97+0xba/0xba > [ 1.760091] kthread+0x112/0x130 > [ 1.760091] ? kthread_flush_work_fn+0x10/0x10 > [ 1.760091] ret_from_fork+0x35/0x40 > [ 89.123011] node 0 initialised, 1055935372 pages in 88650ms > > Fixes: 3a2d7fa8a3d5 ("mm: disable interrupts while initializing deferred pages") > Cc: stable@vger.kernel.org # 4.17+ > > Reported-by: Yiqian Wei > Tested-by: David Hildenbrand > Signed-off-by: Pavel Tatashin > Reviewed-by: Daniel Jordan Acked-by: Michal Hocko > --- > mm/page_alloc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 5ffa8d7e5545..deacfe575872 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1810,7 +1810,7 @@ static int __init deferred_init_memmap(void *data) > */ > while (spfn < epfn) { > nr_pages += deferred_init_maxorder(&i, zone, &spfn, &epfn); > - touch_nmi_watchdog(); > + cond_resched(); > } > zone_empty: > /* Sanity check that the next zone really is unpopulated */ > -- > 2.17.1 -- Michal Hocko SUSE Labs