Commit 6dbb5741 authored Dec 15, 2020 by Alex Shi Committed by Linus Torvalds Dec 15, 2020

mm/thp: simplify lru_add_page_tail()

Simplify lru_add_page_tail(), there are actually only two cases
possible: split_huge_page_to_list(), with list supplied and head
isolated from lru by its caller; or split_huge_page(), with NULL list
and head on lru - because when head is racily isolated from lru, the
isolator's reference will stop the split from getting any further than
its page_ref_freeze().

So decide between the two cases by "list", but add VM_WARN_ON()s to
verify that they match our lru expectations.

[Hugh Dickins: rewrite commit log]

Link: https://lkml.kernel.org/r/1604566549-62481-4-git-send-email-alex.shi@linux.alibaba.com


Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mika Penttilä <mika.penttila@nextfour.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Chen, Rong A" <rong.a.chen@intel.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 94866635

mm/huge_memory.c

+6 −14

Original line number	Diff line number	Diff line
		@@ -2367,24 +2367,16 @@ static void lru_add_page_tail(struct page head, struct page tail,
		VM_BUG_ON_PAGE(PageLRU(tail), head);
		lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);

		if (!list)
		SetPageLRU(tail);

		if (likely(PageLRU(head)))
		list_add_tail(&tail->lru, &head->lru);
		else if (list) {
		if (list) {
		/* page reclaim is reclaiming a huge page */
		VM_WARN_ON(PageLRU(head));
		get_page(tail);
		list_add_tail(&tail->lru, list);
		} else {
		/*
		* Head page has not yet been counted, as an hpage,
		* so we must account for each subpage individually.
		*
		* Put tail on the list at the correct position
		* so they all end up in order.
		*/
		add_page_to_lru_list_tail(tail, lruvec, page_lru(tail));
		/* head is still on lru (and we have it frozen) */
		VM_WARN_ON(!PageLRU(head));
		SetPageLRU(tail);
		list_add_tail(&tail->lru, &head->lru);
		}
		}

Admin message