From: Yu Zhao <yuzhao@google.com>
To: Barry Song <21cnbao@gmail.com>
Cc: "Will Deacon" <will@kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>, "Andi Kleen" <ak@linux.intel.com>,
"Aneesh Kumar" <aneesh.kumar@linux.ibm.com>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Hillf Danton" <hdanton@sina.com>, "Jens Axboe" <axboe@kernel.dk>,
"Johannes Weiner" <hannes@cmpxchg.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Matthew Wilcox" <willy@infradead.org>,
"Mel Gorman" <mgorman@suse.de>,
"Michael Larabel" <Michael@michaellarabel.com>,
"Michal Hocko" <mhocko@kernel.org>,
"Mike Rapoport" <rppt@kernel.org>,
"Peter Zijlstra" <peterz@infradead.org>,
"Tejun Heo" <tj@kernel.org>, "Vlastimil Babka" <vbabka@suse.cz>,
LAK <linux-arm-kernel@lists.infradead.org>,
"Linux Doc Mailing List" <linux-doc@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
"Kernel Page Reclaim v2" <page-reclaim@google.com>,
"Brian Geffon" <bgeffon@google.com>,
"Jan Alexander Steffens" <heftig@archlinux.org>,
"Oleksandr Natalenko" <oleksandr@natalenko.name>,
"Steven Barrett" <steven@liquorix.net>,
"Suleiman Souhlal" <suleiman@google.com>,
"Daniel Byrne" <djbyrne@mtu.edu>,
"Donald Carr" <d@chaos-reins.com>,
"Holger Hoffstätte" <holger@applied-asynchrony.com>,
"Konstantin Kharlamov" <Hi-Angel@yandex.ru>,
"Shuang Zhai" <szhai2@cs.rochester.edu>,
"Sofia Trinh" <sofia.trinh@edi.works>,
"Vaibhav Jain" <vaibhav@linux.ibm.com>,
huzhanyuan@oppo.com
Subject: Re: [PATCH v11 07/14] mm: multi-gen LRU: exploit locality in rmap
Date: Tue, 7 Jun 2022 13:07:11 -0600 [thread overview]
Message-ID: <CAOUHufbi7h6siHdnhsAEiXaCoNrUs9bUnEihYouE4CNMt-Zd_w@mail.gmail.com> (raw)
In-Reply-To: <CAGsJ_4w3S_8Kaw2GyB3hg7b4N_D+6yBO7D6qmgxD9Fqz3_dhAg@mail.gmail.com>
On Tue, Jun 7, 2022 at 1:37 AM Barry Song <21cnbao@gmail.com> wrote:
>
> On Mon, Jun 6, 2022 at 9:25 PM Barry Song <21cnbao@gmail.com> wrote:
> >
> > On Wed, May 18, 2022 at 4:49 PM Yu Zhao <yuzhao@google.com> wrote:
...
> I can't really explain why we are getting a random app/java vm crash in monkey
> test by using ptep_test_and_clear_young() only in lru_gen_look_around() on an
> armv8-a machine without hardware PTE young support.
>
> Moving to ptep_clear_flush_young() in look_around can make the random
> hang disappear according to zhanyuan(Cc-ed).
This sounds too familiar -- let me ask again: was the following commit
included during the test?
07509e10dcc7 arm64: pgtable: Fix pte_accessible()
If not, it will cause exactly the problem you described. And what
about this one?
e914d8f00391 mm: fix unexpected zeroed page mapping with zram swap
Missing it also causes userspace memory corruption on Android, i.e.,
random app crashes.
> On x86, ptep_clear_flush_young() is exactly ptep_test_and_clear_young()
> after
> 'commit b13b1d2d8692 ("x86/mm: In the PTE swapout page reclaim case clear
> the accessed bit instead of flushing the TLB")'
>
> But on arm64, they are different. according to Will's comments in this
> thread which
> tried to make arm64 same with x86,
> https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1793881.html
>
> "
> This is blindly copied from x86 and isn't true for us: we don't invalidate
> the TLB on context switch. That means our window for keeping the stale
> entries around is potentially much bigger and might not be a great idea.
>
> If we roll a TLB invalidation routine without the trailing DSB, what sort of
> performance does that get you?
> "
> We shouldn't think ptep_clear_flush_young() is safe enough in LRU to
> clear PTE young? Any comments from Will?
>
> >
> > btw, lru_gen_look_around() has already included 'address', are we doing
> > pte check for 'address' twice here?
Explained in the previous reply. Hope that clarifies things.
next prev parent reply other threads:[~2022-06-08 1:08 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-18 1:46 [PATCH v11 00/14] Multi-Gen LRU Framework Yu Zhao
2022-05-18 1:46 ` [PATCH v11 01/14] mm: x86, arm64: add arch_has_hw_pte_young() Yu Zhao
2022-05-18 1:46 ` [PATCH v11 02/14] mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG Yu Zhao
2022-05-18 1:46 ` [PATCH v11 03/14] mm/vmscan.c: refactor shrink_node() Yu Zhao
2022-05-18 1:46 ` [PATCH v11 04/14] Revert "include/linux/mm_inline.h: fold __update_lru_size() into its sole caller" Yu Zhao
2022-05-18 1:46 ` [PATCH v11 05/14] mm: multi-gen LRU: groundwork Yu Zhao
2022-06-09 5:33 ` zhong jiang
2022-05-18 1:46 ` [PATCH v11 06/14] mm: multi-gen LRU: minimal implementation Yu Zhao
2022-06-09 12:34 ` zhong jiang
2022-06-09 14:46 ` zhong jiang
2022-05-18 1:46 ` [PATCH v11 07/14] mm: multi-gen LRU: exploit locality in rmap Yu Zhao
2022-06-06 9:25 ` Barry Song
2022-06-07 7:37 ` Barry Song
2022-06-07 10:21 ` Will Deacon
2022-06-06 22:37 ` Barry Song
2022-06-07 10:43 ` Will Deacon
2022-06-07 21:06 ` Yu Zhao
2022-06-08 0:43 ` Barry Song
2022-06-08 15:51 ` Linus Torvalds
2022-06-08 22:45 ` Barry Song
2022-06-16 21:55 ` Yu Zhao
2022-06-16 22:33 ` Barry Song
2022-06-16 23:29 ` Yu Zhao
2022-06-17 1:42 ` Yu Zhao
2022-06-17 2:01 ` Barry Song
2022-06-17 3:03 ` Yu Zhao
2022-06-17 3:17 ` Yu Zhao
2022-06-19 20:36 ` Yu Zhao
2022-06-19 21:56 ` Barry Song
2022-06-07 19:07 ` Yu Zhao [this message]
2022-06-08 7:48 ` Barry Song
2022-06-07 18:58 ` Yu Zhao
2022-05-18 1:46 ` [PATCH v11 08/14] mm: multi-gen LRU: support page table walks Yu Zhao
2022-05-18 1:46 ` [PATCH v11 09/14] mm: multi-gen LRU: optimize multiple memcgs Yu Zhao
2022-05-18 1:46 ` [PATCH v11 10/14] mm: multi-gen LRU: kill switch Yu Zhao
2022-05-18 1:46 ` [PATCH v11 11/14] mm: multi-gen LRU: thrashing prevention Yu Zhao
2022-05-18 1:46 ` [PATCH v11 12/14] mm: multi-gen LRU: debugfs interface Yu Zhao
2022-05-18 1:46 ` [PATCH v11 13/14] mm: multi-gen LRU: admin guide Yu Zhao
2022-05-18 1:46 ` [PATCH v11 14/14] mm: multi-gen LRU: design doc Yu Zhao
2022-05-18 2:05 ` [PATCH v11 00/14] Multi-Gen LRU Framework Jens Axboe
2022-06-07 22:47 ` Yu Zhao
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