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AJvYcCX6VfhBtVtO2qAsEP7YDGFpIM4idVCISrPSyK1KLrHpw/MA6Lqs+2CvR02MMMvPnKu3s3o1d5diIg==@kvack.org X-Gm-Message-State: AOJu0YxigusBBR+Wyalb+bx42x15It5NIdFZ9LPPEwCXbHcirQ28fgcW PZIMiYbz0As6dIu6ZkAw8Fb8aNxC3dBeF1yfp07lm+HP88MTIqu29l70BHhjvDmonJNXG6AJfiE ahb12sxv+0GL/hqyNwNeKVTuwlS6lD3ZOlzBj X-Gm-Gg: ASbGncsQ2tO8FUoeC63aDwMJddBIsaPSd1pFNS9vk7xnl0QFqUr0ZOVcnIB587Bzmzh MxRdByWmSEiy7r2trGj0h0223i5ISU9+bzOwsD3N5z7AgVKdCHlwfFGckdHf3xyHbERRnTWrPpz AM0avFxP9CZ3gKyjwE3exvTw== X-Google-Smtp-Source: AGHT+IE5n+RYFL33clCtYhMDflCfi8b/wULONOuhv9hsef7TFhR/zEdhdJST2xupcNv0DfmIPfytbRz9d2S6+NTJu+U= X-Received: by 2002:a05:6402:340e:b0:5e0:eaa6:a2b0 with SMTP id 4fb4d7f45d1cf-5fc6db9ae62mr87747a12.5.1746718072728; Thu, 08 May 2025 08:27:52 -0700 (PDT) MIME-Version: 1.0 References: <20250508090735.39756-1-21cnbao@gmail.com> In-Reply-To: From: Lokesh Gidra Date: Thu, 8 May 2025 08:27:39 -0700 X-Gm-Features: ATxdqUEEUE1zAqS3YeD7cRcnIVxj-q-7a3F2R2n84xjSXGLUSt2BDd1V-vHoAIk Message-ID: Subject: Re: [PATCH RFC] mm: userfaultfd: correct dirty flags set for both present and swap pte To: Peter Xu Cc: Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Barry Song , David Hildenbrand , Suren Baghdasaryan , Kalesh Singh Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 9769B20009 X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: qcdw5yctzq8zuy1bp1wwdegeacyefupj X-HE-Tag: 1746718074-959938 X-HE-Meta: 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 xz8jUyBS zFDTNaLfaXaNzbBx/P/RclZcZRx9s1wfAJa/6IsZwt2k0dB9aZZKVU4vP3oikk8XcN4q+2qrrk54JoO1LbAU7XW/V6PLqIy5h7bgKD2Ww7NXx6Kk48pvqRM0msgPYjnc2FpzYBtsF31XMS9fl3Rx7XEnbgfPGjpiV3twyRwjySY2Q3Akq7ZiVITo12Icg/66BZC+DilTifZjOCF7sxKe8Mw4BqP/lwmzDCuitCA8Ej8oRuTpUSylJBojAYSa9beGtuMsU5NkaUcw4gzGI3wm00WXVav7cvFlfRWQM 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: List-Subscribe: List-Unsubscribe: Thanks Barry for fixing this. On Thu, May 8, 2025 at 8:24=E2=80=AFAM Peter Xu wrote: > > On Thu, May 08, 2025 at 09:07:35PM +1200, Barry Song wrote: > > From: Barry Song > > > > As David pointed out, what truly matters for mremap and userfaultfd > > move operations is the soft dirty bit. The current comment and > > implementation=E2=80=94which always sets the dirty bit for present PTEs > > and fails to set the soft dirty bit for swap PTEs=E2=80=94are incorrect= . Can you please briefly describe the consequences of not setting the soft-dirty bit? I'm wondering if it needs to be backported as a fix? > > This patch updates the behavior to correctly set the soft dirty bit > > for both present and swap PTEs in accordance with mremap. > > > > Reported-by: David Hildenbrand > > Closes: https://lore.kernel.org/linux-mm/02f14ee1-923f-47e3-a994-4950af= b9afcc@redhat.com/ > > Cc: Peter Xu > > Cc: Suren Baghdasaryan > > Cc: Lokesh Gidra > > Signed-off-by: Barry Song > > Acked-by: Peter Xu > > -- > Peter Xu >