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d=linux-foundation.org; s=korg; t=1690402719; bh=MMioSWLe0J+F5cA3VOGFUM/YW6sX+D23b5MfVPZqMwg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=BAp862XDg5jm4GYl6C/MPJCbU0NcJd6qPBVRi+my42pt/DpGQq+SWl6YIT7fPp2PL HcTDTo7GooY8BqKKq/e9K45b7acdnf/8e4JgzivN0rxkQUcPLhm+263tGJc5Oa2wxs G7HZ6q+3UPSjZyikhKl7/dD9hL3rjG9tai4JLO+c= Date: Wed, 26 Jul 2023 13:18:22 -0700 From: Andrew Morton To: Andrew Yang (=?UTF-8?B?5qWK5pm65by3?=) Cc: "senozhatsky@chromium.org" , "bigeasy@linutronix.de" , "linux-kernel@vger.kernel.org" , "linux-mediatek@lists.infradead.org" , "linux-mm@kvack.org" , wsd_upstream , Casper Li (=?UTF-8?B?5p2O5Lit5qau?=) , "minchan@kernel.org" , "linux-arm-kernel@lists.infradead.org" , "matthias.bgg@gmail.com" , "angelogioacchino.delregno@collabora.com" Subject: Re: [PATCH] zsmalloc: Fix races between modifications of fullness and isolated Message-Id: <20230726131822.22ac039ee4c696ea0726b510@linux-foundation.org> In-Reply-To: <42f1209a686404ffd0f9dff05ed10a8d23383a11.camel@mediatek.com> References: <20230721063705.11455-1-andrew.yang@mediatek.com> <20230726031846.GJ955071@google.com> <42f1209a686404ffd0f9dff05ed10a8d23383a11.camel@mediatek.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: wqd59yy1y9ca57otof4amue37asf4848 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: AECA68001F X-HE-Tag: 1690402720-913749 X-HE-Meta: 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 Mr5arioJ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, 26 Jul 2023 06:59:20 +0000 Andrew Yang (楊智強) wrote: > > Have you observed issues in real life? That commit is more than a > > year > > and a half old, so I wonder. > > > Yes, we encountered many kernel exceptions of > VM_BUG_ON(zspage->isolated == 0) in dec_zspage_isolation() and > BUG_ON(!pages[1]) in zs_unmap_object() lately. > This issue only occurs when migration and reclamation occur at the > same time. With our memory stress test, we can reproduce this issue > several times a day. We have no idea why no one else encountered > this issue. BTW, we switched to the new kernel version with this > defect a few months ago. Ah. It's important that such information be in the changelog! I have put this info into my copy of the v1 patch's changelog. I have moved the v1 patch from the mm-unstable branch into mm-hotfixes-unstable, so it is staged for merging in this -rc cycle. I have also added a cc:stable so that the fix gets backported into kernels which contain c4549b871102. I have added a note-to-self that a v2 patch is expected.