From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 049/131] mm/pagealloc.c: call touch_nmi_watchdog() on max order boundaries in deferred init Date: Wed, 03 Jun 2020 15:59:20 -0700 Message-ID: <20200603225920.fbzmRRTEg%akpm@linux-foundation.org> References: <20200603155549.e041363450869eaae4c7f05b@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:41398 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725821AbgFCW7W (ORCPT ); Wed, 3 Jun 2020 18:59:22 -0400 In-Reply-To: <20200603155549.e041363450869eaae4c7f05b@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, dan.j.williams@intel.com, daniel.m.jordan@oracle.com, david@redhat.com, jmorris@namei.org, ktkhai@virtuozzo.com, linux-mm@kvack.org, mhocko@suse.com, mm-commits@vger.kernel.org, pasha.tatashin@soleen.com, sashal@kernel.org, shile.zhang@linux.alibaba.com, stable@vger.kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz, yiwei@redhat.com From: Daniel Jordan Subject: mm/pagealloc.c: call touch_nmi_watchdog() on max order boundaries in deferred init Patch series "initialize deferred pages with interrupts enabled", v4. Keep interrupts enabled during deferred page initialization in order to make code more modular and allow jiffies to update. Original approach, and discussion can be found here: http://lkml.kernel.org/r/20200311123848.118638-1-shile.zhang@linux.alibaba.com This patch (of 3): deferred_init_memmap() disables interrupts the entire time, so it calls touch_nmi_watchdog() periodically to avoid soft lockup splats. Soon it will run with interrupts enabled, at which point cond_resched() should be used instead. deferred_grow_zone() makes the same watchdog calls through code shared with deferred init but will continue to run with interrupts disabled, so it can't call cond_resched(). Pull the watchdog calls up to these two places to allow the first to be changed later, independently of the second. The frequency reduces from twice per pageblock (init and free) to once per max order block. Link: http://lkml.kernel.org/r/20200403140952.17177-2-pasha.tatashin@soleen.com Fixes: 3a2d7fa8a3d5 ("mm: disable interrupts while initializing deferred pages") Signed-off-by: Daniel Jordan Signed-off-by: Pavel Tatashin Reviewed-by: David Hildenbrand Acked-by: Michal Hocko Acked-by: Vlastimil Babka Cc: Dan Williams Cc: Shile Zhang Cc: Kirill Tkhai Cc: James Morris Cc: Sasha Levin Cc: Yiqian Wei Cc: [4.17+] Signed-off-by: Andrew Morton --- mm/page_alloc.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/mm/page_alloc.c~mm-call-touch_nmi_watchdog-on-max-order-boundaries-in-deferred-init +++ a/mm/page_alloc.c @@ -1693,7 +1693,6 @@ static void __init deferred_free_pages(u } else if (!(pfn & nr_pgmask)) { deferred_free_range(pfn - nr_free, nr_free); nr_free = 1; - touch_nmi_watchdog(); } else { nr_free++; } @@ -1723,7 +1722,6 @@ static unsigned long __init deferred_in continue; } else if (!page || !(pfn & nr_pgmask)) { page = pfn_to_page(pfn); - touch_nmi_watchdog(); } else { page++; } @@ -1863,8 +1861,10 @@ static int __init deferred_init_memmap(v * that we can avoid introducing any issues with the buddy * allocator. */ - while (spfn < epfn) + while (spfn < epfn) { nr_pages += deferred_init_maxorder(&i, zone, &spfn, &epfn); + touch_nmi_watchdog(); + } zone_empty: pgdat_resize_unlock(pgdat, &flags); @@ -1948,6 +1948,7 @@ deferred_grow_zone(struct zone *zone, un first_deferred_pfn = spfn; nr_pages += deferred_init_maxorder(&i, zone, &spfn, &epfn); + touch_nmi_watchdog(); /* We should only stop along section boundaries */ if ((first_deferred_pfn ^ spfn) < PAGES_PER_SECTION) _