The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 117003c32771df617acf66e140fbdbdeb0ac71f5 Mon Sep 17 00:00:00 2001

From: Daniel Jordan daniel.m.jordan@oracle.com Date: Wed, 3 Jun 2020 15:59:20 -0700 Subject: [PATCH] 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.c...

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.

Fixes: 3a2d7fa8a3d5 ("mm: disable interrupts while initializing deferred pages") Signed-off-by: Daniel Jordan daniel.m.jordan@oracle.com Signed-off-by: Pavel Tatashin pasha.tatashin@soleen.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Reviewed-by: David Hildenbrand david@redhat.com Acked-by: Michal Hocko mhocko@suse.com Acked-by: Vlastimil Babka vbabka@suse.cz Cc: Dan Williams dan.j.williams@intel.com Cc: Shile Zhang shile.zhang@linux.alibaba.com Cc: Kirill Tkhai ktkhai@virtuozzo.com Cc: James Morris jmorris@namei.org Cc: Sasha Levin sashal@kernel.org Cc: Yiqian Wei yiwei@redhat.com Cc: stable@vger.kernel.org [4.17+] Link: http://lkml.kernel.org/r/20200403140952.17177-2-pasha.tatashin@soleen.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org

diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 045c4aeeec9a..148cf9a73f0b 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1693,7 +1693,6 @@ static void __init deferred_free_pages(unsigned long pfn, } 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_init_pages(struct zone *zone, 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(void *data) * 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, unsigned int order) 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)