linux-kernel - Re: [PATCH 04/47] LoongArch: Set _PAGE_DIRTY only if _PAGE_WRITE is set in {pmd,pte}

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Message-ID: <b402098421927699db853e5e05fbb9d48fa24886.camel@xry111.site>
Date:   Thu, 17 Nov 2022 23:42:17 +0800
From:   Xi Ruoyao <xry111@...111.site>
To:     Huacai Chen <chenhuacai@...ngson.cn>,
        Huacai Chen <chenhuacai@...nel.org>
Cc:     loongarch@...ts.linux.dev, Xuefeng Li <lixuefeng@...ngson.cn>,
        Guo Ren <guoren@...nel.org>, Xuerui Wang <kernel@...0n.name>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        "David S . Miller" <davem@...emloft.net>,
        sparclinux@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, Peter Xu <peterx@...hat.com>
Subject: Re: [PATCH 04/47] LoongArch: Set _PAGE_DIRTY only if _PAGE_WRITE is
 set in {pmd,pte}_mkdirty()

On Thu, 2022-11-17 at 21:59 +0800, Xi Ruoyao wrote:
> Hi Huacai,
> 
> On Thu, 2022-11-17 at 12:25 +0800, Huacai Chen wrote:
> > Now {pmd,pte}_mkdirty() set _PAGE_DIRTY bit unconditionally, this causes
> > random segmentation fault after commit 0ccf7f168e17bb7e ("mm/thp: carry
> > over dirty bit when thp splits on pmd").
> 
> Hmm, the pte_mkdirty call is already removed in commit 624a2c94f5b7a081
> ("Partly revert \"mm/thp: carry over dirty bit when thp splits on
> pmd\"").
> 
> Not sure if this issue is related to some random segfaults I've observed
> recently though.  My last kernel build contains 0ccf7f168e17bb7e but
> does not contain 624a2c94f5b7a081.

I can confirm this patch alone (without 624a2c94f5b7a081) fixes the
random segfaults I've recently encountered running GCC testsuite.

Link: https://gcc.gnu.org/pipermail/gcc/2022-November/239857.html
Tested-by: Xi Ruoyao <xry111@...111.site>

-- 
Xi Ruoyao <xry111@...111.site>
School of Aerospace Science and Technology, Xidian University