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AJvYcCVKozqkGMn6eut222qyjH+9QrYEZqM6XISilhrLZCQyOs1lWVnk8ZIRsE/lLQj6sp4nIDijLtRc+y3b1B7h9j78Qac= X-Gm-Message-State: AOJu0YxWjpTsRvizFY62P+U+VABQGV0Gyd5aOYAHHZo2Ha/7qXcr+USj lERuvzsuZ/8aznXOzACa9hiHwxYfRTJtdalOKWlsBcq7KNAwxPXGgx25DIpu4dAFplDKk91SYGj lfFIoK6gecvaPws0AL0gI1gTaFguJUyAwtkZa X-Google-Smtp-Source: AGHT+IFmgRVvi5T0P1Czc7H/RoVAFBHNXb7TfGgkcvEuKJD6OdVQOUibgYRqWAU/Ms6SXyWzass5Lmaf9TDZOL/tCgY= X-Received: by 2002:a81:ad07:0:b0:607:d5c7:6a8a with SMTP id l7-20020a81ad07000000b00607d5c76a8amr455225ywh.25.1708639014981; Thu, 22 Feb 2024 13:56:54 -0800 (PST) MIME-Version: 1.0 References: <20240222080815.46291-1-zhengqi.arch@bytedance.com> <20240222130005.c3f24eed1c1a27c66947e9df@linux-foundation.org> In-Reply-To: <20240222130005.c3f24eed1c1a27c66947e9df@linux-foundation.org> From: Suren Baghdasaryan Date: Thu, 22 Feb 2024 13:56:44 -0800 Message-ID: Subject: Re: [PATCH] mm: userfaultfd: fix unexpected change to src_folio when UFFDIO_MOVE fails To: Andrew Morton Cc: Qi Zheng , aarcange@redhat.com, david@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 22AA840003 X-Stat-Signature: g4kky8pnzu6r3m6pouan4wo3nbxr7xqo X-HE-Tag: 1708639015-680062 X-HE-Meta: U2FsdGVkX18RNDQ3xYHunhxuuVzdx806/l/zSuiy1vmnbSa6B57mq1SWJCkjlW7noAwdedoZQ5u+9oKlGFUAcxybfLfCgVhOJUH6hfTsa8XRGClcA2s6bLiT93Wggu94t9+wOvZr6cpGMDSOoXy6corC6YWFYyJAYCDj5ypv6+2CrBspaONcW7GfgX0pwfBqguxsz69NlQwnN94/o6oCsm98ROAB9UikA+ZazY3N0G6JY5G7hv+VDpJ4E5FCezXQ0DOheAbfXRiyGD832L69x4BoaeiBeO5VVVCbkLtwS1trRxQ4ko1mGHuI2IM7EPpOSZE5pKG8Bw663KwkrOS616WE3+2n3zOm8GixMFQXJoTHAr8/19WSfwSkDZ/dAU2VFaTmPCrAmvL6WSQ4WfInLa/U2Dvlv+dPs5nB/uvoD3wMeiobXE7V7kzMno+P63evs20JLI1Mr94mpw+ErMLL1khi8Yt9H12fDQLacqUmxV+6Y4dj7lKcQ8p305Jh5bFqSlQY/t0ewP4JjZlRF82xODtsW964xYSpVSoZ9hYJV3sXLLoqFwsHdxDTmmtz2PwJLyGdb2fBHM6I9g++/uoY9onoZgZb1OZEg1qt+mdZ3Jb5HqCukBVFIsyKpF9S5o1wPljgoblzAuG1iG8zJvuFZ62ASqUxf8i9s9ikdGY3GY8SJSFhwG0d/Gkx+C1lsizh3tYFqNUj55x4vJqN8g1wg0U4dz5L4aGEmibVbO08iOhTcSrf5N1iojUwD4pu4q+InTDgwBxD21asaZaNGaAQamm4trs1kqm9l7g3OVcHG+hDNeFGZn+Il6v3W+dP1Y+6jjiL0U0SprDNzLx+q+mjlOqEI8+CjoNNt/RVIPVdKVpjtt3OLaJJwvvBfeoqELLvPtEWtDbPgd2MkRGJc0+iJKBUA2xlFCtfmlCUXnNNJy3+6ITX1yaD6l+ilUy7ewM7H3yUvlVxWoJWRunwvkx rcHzhWpb G6LbiPhQTEVFRP9sc/xfAktm/mHnFMN8zJK3M X-Bogosity: Ham, tests=bogofilter, spamicity=0.081843, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Feb 22, 2024 at 1:00=E2=80=AFPM Andrew Morton wrote: > > On Thu, 22 Feb 2024 16:08:15 +0800 Qi Zheng = wrote: > > > After ptep_clear_flush(), if we find that src_folio is pinned we will f= ail > > UFFDIO_MOVE and put src_folio back to src_pte entry, but the change to > > src_folio->{mapping,index} is not restored in this process. This is not > > what we expected, so fix it. > > > > Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI") > > What are the expected worst-case userspace-visible runtime effects of > this flaw? It can cause rmap for that page to be invalid. I guess memory corruption might be the visible effect?