From: Alex Shi <alex.shi@linux.alibaba.com> To: Alexander Duyck <alexander.duyck@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mgorman@techsingularity.net>, Tejun Heo <tj@kernel.org>, Hugh Dickins <hughd@google.com>, Konstantin Khlebnikov <khlebnikov@yandex-team.ru>, Daniel Jordan <daniel.m.jordan@oracle.com>, Yang Shi <yang.shi@linux.alibaba.com>, Matthew Wilcox <willy@infradead.org>, Johannes Weiner <hannes@cmpxchg.org>, kbuild test robot <lkp@intel.com>, linux-mm <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, cgroups@vger.kernel.org, Shakeel Butt <shakeelb@google.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Wei Yang <richard.weiyang@gmail.com>, "Kirill A. Shutemov" <kirill@shutemov.name> Subject: Re: [PATCH v16 15/22] mm/compaction: do page isolation first in compaction Date: Fri, 17 Jul 2020 13:09:43 +0800 [thread overview] Message-ID: <e724c44b-4135-3302-16fa-1df624fa81fa@linux.alibaba.com> (raw) In-Reply-To: <CAKgT0Ue72SfAmxCS+tay1NjioW9WBOvVgrhwUtVPz2aDCrcHPQ@mail.gmail.com> >> @@ -950,6 +951,21 @@ static bool too_many_isolated(pg_data_t *pgdat) >> if (!(cc->gfp_mask & __GFP_FS) && page_mapping(page)) >> goto isolate_fail; >> >> + /* >> + * Be careful not to clear PageLRU until after we're >> + * sure the page is not being freed elsewhere -- the >> + * page release code relies on it. >> + */ >> + if (unlikely(!get_page_unless_zero(page))) >> + goto isolate_fail; >> + >> + if (__isolate_lru_page_prepare(page, isolate_mode) != 0) >> + goto isolate_fail_put; >> + >> + /* Try isolate the page */ >> + if (!TestClearPageLRU(page)) >> + goto isolate_fail_put; >> + >> /* If we already hold the lock, we can skip some rechecking */ >> if (!locked) { >> locked = compact_lock_irqsave(&pgdat->lru_lock, > > Why not do the __isolate_lru_page_prepare before getting the page? > That way you can avoid performing an extra atomic operation on non-LRU > pages. > This change come from Hugh Dickins as mentioned from commit log: >> trylock_page() is not safe to use at this time: its setting PG_locked >> can race with the page being freed or allocated ("Bad page"), and can >> also erase flags being set by one of those "sole owners" of a freshly >> allocated page who use non-atomic __SetPageFlag(). Hi Hugh, would you like to show more details of the bug? ... >> + * sure the page is not being freed elsewhere -- the >> + * page release code relies on it. >> + */ >> + if (unlikely(!get_page_unless_zero(page))) >> + goto busy; >> + >> + if (!TestClearPageLRU(page)) { >> + /* >> + * This page may in other isolation path, >> + * but we still hold lru_lock. >> + */ >> + put_page(page); >> + goto busy; >> + } >> + > > I wonder if it wouldn't make sense to combine these two atomic ops > with tests and the put_page into a single inline function? Then it > could be possible to just do one check and if succeeds you do the > block of code below, otherwise you just fall-through into the -EBUSY > case. > Uh, since get_page changes page->_refcount, TestClearPageLRU changes page->flags, So I don't know how to combine them, could you make it more clear with code? Thanks Alex
WARNING: multiple messages have this Message-ID (diff)
From: Alex Shi <alex.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org> To: Alexander Duyck <alexander.duyck-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Mel Gorman <mgorman-3eNAlZScCAx27rWaFMvyedHuzzzSOjJt@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Konstantin Khlebnikov <khlebnikov-XoJtRXgx1JseBXzfvpsJ4g@public.gmane.org>, Daniel Jordan <daniel.m.jordan-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>, Yang Shi <yang.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>, Matthew Wilcox <willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, kbuild test robot <lkp-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, linux-mm <linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>, LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Joonsoo Kim <iamjoonsoo.kim-Hm3cg6mZ9cc@public.gmane.org>, Wei Yang <richard.weiyang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, "Kirill A. Shutemov" <kirill-oKw7cIdHH8eLwutG50LtGA@public.gmane.org> Subject: Re: [PATCH v16 15/22] mm/compaction: do page isolation first in compaction Date: Fri, 17 Jul 2020 13:09:43 +0800 [thread overview] Message-ID: <e724c44b-4135-3302-16fa-1df624fa81fa@linux.alibaba.com> (raw) In-Reply-To: <CAKgT0Ue72SfAmxCS+tay1NjioW9WBOvVgrhwUtVPz2aDCrcHPQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> >> @@ -950,6 +951,21 @@ static bool too_many_isolated(pg_data_t *pgdat) >> if (!(cc->gfp_mask & __GFP_FS) && page_mapping(page)) >> goto isolate_fail; >> >> + /* >> + * Be careful not to clear PageLRU until after we're >> + * sure the page is not being freed elsewhere -- the >> + * page release code relies on it. >> + */ >> + if (unlikely(!get_page_unless_zero(page))) >> + goto isolate_fail; >> + >> + if (__isolate_lru_page_prepare(page, isolate_mode) != 0) >> + goto isolate_fail_put; >> + >> + /* Try isolate the page */ >> + if (!TestClearPageLRU(page)) >> + goto isolate_fail_put; >> + >> /* If we already hold the lock, we can skip some rechecking */ >> if (!locked) { >> locked = compact_lock_irqsave(&pgdat->lru_lock, > > Why not do the __isolate_lru_page_prepare before getting the page? > That way you can avoid performing an extra atomic operation on non-LRU > pages. > This change come from Hugh Dickins as mentioned from commit log: >> trylock_page() is not safe to use at this time: its setting PG_locked >> can race with the page being freed or allocated ("Bad page"), and can >> also erase flags being set by one of those "sole owners" of a freshly >> allocated page who use non-atomic __SetPageFlag(). Hi Hugh, would you like to show more details of the bug? ... >> + * sure the page is not being freed elsewhere -- the >> + * page release code relies on it. >> + */ >> + if (unlikely(!get_page_unless_zero(page))) >> + goto busy; >> + >> + if (!TestClearPageLRU(page)) { >> + /* >> + * This page may in other isolation path, >> + * but we still hold lru_lock. >> + */ >> + put_page(page); >> + goto busy; >> + } >> + > > I wonder if it wouldn't make sense to combine these two atomic ops > with tests and the put_page into a single inline function? Then it > could be possible to just do one check and if succeeds you do the > block of code below, otherwise you just fall-through into the -EBUSY > case. > Uh, since get_page changes page->_refcount, TestClearPageLRU changes page->flags, So I don't know how to combine them, could you make it more clear with code? Thanks Alex
next prev parent reply other threads:[~2020-07-17 5:11 UTC|newest] Thread overview: 125+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-11 0:58 [PATCH v16 00/22] per memcg lru_lock Alex Shi 2020-07-11 0:58 ` [PATCH v16 01/22] mm/vmscan: remove unnecessary lruvec adding Alex Shi 2020-07-11 0:58 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 02/22] mm/page_idle: no unlikely double check for idle page counting Alex Shi 2020-07-11 0:58 ` [PATCH v16 03/22] mm/compaction: correct the comments of compact_defer_shift Alex Shi 2020-07-11 0:58 ` [PATCH v16 04/22] mm/compaction: rename compact_deferred as compact_should_defer Alex Shi 2020-07-11 0:58 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 05/22] mm/thp: move lru_add_page_tail func to huge_memory.c Alex Shi 2020-07-16 8:59 ` Alex Shi 2020-07-16 8:59 ` Alex Shi 2020-07-16 13:17 ` Kirill A. Shutemov 2020-07-16 13:17 ` Kirill A. Shutemov 2020-07-17 5:13 ` Alex Shi 2020-07-17 5:13 ` Alex Shi 2020-07-20 8:37 ` Kirill A. Shutemov 2020-07-20 8:37 ` Kirill A. Shutemov 2020-07-11 0:58 ` [PATCH v16 06/22] mm/thp: clean up lru_add_page_tail Alex Shi 2020-07-11 0:58 ` Alex Shi 2020-07-20 8:43 ` Kirill A. Shutemov 2020-07-20 8:43 ` Kirill A. Shutemov 2020-07-11 0:58 ` [PATCH v16 07/22] mm/thp: remove code path which never got into Alex Shi 2020-07-20 8:43 ` Kirill A. Shutemov 2020-07-20 8:43 ` Kirill A. Shutemov 2020-07-11 0:58 ` [PATCH v16 08/22] mm/thp: narrow lru locking Alex Shi 2020-07-11 0:58 ` [PATCH v16 09/22] mm/memcg: add debug checking in lock_page_memcg Alex Shi 2020-07-11 0:58 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 10/22] mm/swap: fold vm event PGROTATED into pagevec_move_tail_fn Alex Shi 2020-07-11 0:58 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 11/22] mm/lru: move lru_lock holding in func lru_note_cost_page Alex Shi 2020-07-11 0:58 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 12/22] mm/lru: move lock into lru_note_cost Alex Shi 2020-07-11 0:58 ` [PATCH v16 13/22] mm/lru: introduce TestClearPageLRU Alex Shi 2020-07-11 0:58 ` Alex Shi 2020-07-16 9:06 ` Alex Shi 2020-07-16 9:06 ` Alex Shi 2020-07-16 21:12 ` Alexander Duyck 2020-07-16 21:12 ` Alexander Duyck 2020-07-16 21:12 ` Alexander Duyck 2020-07-17 7:45 ` Alex Shi 2020-07-17 7:45 ` Alex Shi 2020-07-17 18:26 ` Alexander Duyck 2020-07-17 18:26 ` Alexander Duyck 2020-07-19 4:45 ` Alex Shi 2020-07-19 4:45 ` Alex Shi 2020-07-19 11:24 ` Alex Shi 2020-07-19 11:24 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 14/22] mm/thp: add tail pages into lru anyway in split_huge_page() Alex Shi 2020-07-11 0:58 ` Alex Shi 2020-07-17 9:30 ` Alex Shi 2020-07-17 9:30 ` Alex Shi 2020-07-20 8:49 ` Kirill A. Shutemov 2020-07-20 8:49 ` Kirill A. Shutemov 2020-07-20 9:04 ` Alex Shi 2020-07-20 9:04 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 15/22] mm/compaction: do page isolation first in compaction Alex Shi 2020-07-16 21:32 ` Alexander Duyck 2020-07-16 21:32 ` Alexander Duyck 2020-07-16 21:32 ` Alexander Duyck 2020-07-17 5:09 ` Alex Shi [this message] 2020-07-17 5:09 ` Alex Shi 2020-07-17 16:09 ` Alexander Duyck 2020-07-17 16:09 ` Alexander Duyck 2020-07-17 16:09 ` Alexander Duyck 2020-07-19 3:59 ` Alex Shi 2020-07-19 3:59 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 16/22] mm/mlock: reorder isolation sequence during munlock Alex Shi 2020-07-17 20:30 ` Alexander Duyck 2020-07-17 20:30 ` Alexander Duyck 2020-07-17 20:30 ` Alexander Duyck 2020-07-19 3:55 ` Alex Shi 2020-07-19 3:55 ` Alex Shi 2020-07-20 18:51 ` Alexander Duyck 2020-07-20 18:51 ` Alexander Duyck 2020-07-20 18:51 ` Alexander Duyck 2020-07-21 9:26 ` Alex Shi 2020-07-21 9:26 ` Alex Shi 2020-07-21 13:51 ` Alex Shi 2020-07-21 13:51 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 17/22] mm/swap: serialize memcg changes during pagevec_lru_move_fn Alex Shi 2020-07-11 0:58 ` [PATCH v16 18/22] mm/lru: replace pgdat lru_lock with lruvec lock Alex Shi 2020-07-11 0:58 ` Alex Shi 2020-07-17 21:38 ` Alexander Duyck 2020-07-17 21:38 ` Alexander Duyck 2020-07-17 21:38 ` Alexander Duyck 2020-07-18 14:15 ` Alex Shi 2020-07-19 9:12 ` Alex Shi 2020-07-19 9:12 ` Alex Shi 2020-07-19 15:14 ` Alexander Duyck 2020-07-19 15:14 ` Alexander Duyck 2020-07-19 15:14 ` Alexander Duyck 2020-07-20 5:47 ` Alex Shi 2020-07-20 5:47 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 19/22] mm/lru: introduce the relock_page_lruvec function Alex Shi 2020-07-11 0:58 ` Alex Shi 2020-07-17 22:03 ` Alexander Duyck 2020-07-17 22:03 ` Alexander Duyck 2020-07-18 14:01 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 20/22] mm/vmscan: use relock for move_pages_to_lru Alex Shi 2020-07-17 21:44 ` Alexander Duyck 2020-07-17 21:44 ` Alexander Duyck 2020-07-17 21:44 ` Alexander Duyck 2020-07-18 14:15 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 21/22] mm/pgdat: remove pgdat lru_lock Alex Shi 2020-07-17 21:09 ` Alexander Duyck 2020-07-17 21:09 ` Alexander Duyck 2020-07-18 14:17 ` Alex Shi 2020-07-18 14:17 ` Alex Shi 2020-07-11 0:58 ` [PATCH v16 22/22] mm/lru: revise the comments of lru_lock Alex Shi 2020-07-11 1:02 ` [PATCH v16 00/22] per memcg lru_lock Alex Shi 2020-07-11 1:02 ` Alex Shi 2020-07-16 8:49 ` Alex Shi 2020-07-16 14:11 ` Alexander Duyck 2020-07-16 14:11 ` Alexander Duyck 2020-07-16 14:11 ` Alexander Duyck 2020-07-17 5:24 ` Alex Shi 2020-07-17 5:24 ` Alex Shi 2020-07-19 15:23 ` Hugh Dickins 2020-07-19 15:23 ` Hugh Dickins 2020-07-20 3:01 ` Alex Shi 2020-07-20 3:01 ` Alex Shi 2020-07-20 4:47 ` Hugh Dickins 2020-07-20 4:47 ` Hugh Dickins 2020-07-20 4:47 ` Hugh Dickins 2020-07-20 7:30 ` Alex Shi 2020-07-20 7:30 ` Alex Shi
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