linux-kernel - Re: [PATCH] zsmalloc: Fix races between modifications of fullness and isolated

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <20230726131822.22ac039ee4c696ea0726b510@linux-foundation.org>
Date:   Wed, 26 Jul 2023 13:18:22 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Andrew Yang (楊智強) <Andrew.Yang@...iatek.com>
Cc:     "senozhatsky@...omium.org" <senozhatsky@...omium.org>,
        "bigeasy@...utronix.de" <bigeasy@...utronix.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        wsd_upstream <wsd_upstream@...iatek.com>,
        Casper Li (李中榮) <casper.li@...iatek.com>,
        "minchan@...nel.org" <minchan@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>
Subject: Re: [PATCH] zsmalloc: Fix races between modifications of fullness
 and isolated

On Wed, 26 Jul 2023 06:59:20 +0000 Andrew Yang (楊智強) <Andrew.Yang@...iatek.com> 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.