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AJvYcCWGw4Ip3PJSKPski2oARfD69LO7j5etpsKbLauW9Pj8XiI+kGFox+piENIvNGWrQgQpsayyjnWFDg==@kvack.org X-Gm-Message-State: AOJu0Yx6ILOiKC1KEhirv/A0owzlkfOTWRF1K0U3vGYyZ9jWxYqTFOoo 7V6Ft8f4BhBG0IxWV9x0mSQbo/NK4U9FdzWrecYN1n+3IaCkFiXTYCIMqV5mQGaXJLIgUp9oRmr ivMRgv4sYDphzsGf4iacZLudMvj78gPQ= X-Gm-Gg: ASbGncsMSa9Pb38yWhMsQSf5ubLs5SoZmXI5joOi87NskSITjaJ/pMfERlxJaWSFVDH qq7VN0UZ6mMukZYvSLjMuZtrInvaZVGRB6kHzMEGxXbyUXBOXJDNzzS7LYcpafTgyDLhFqMJc3l ELqUZqLqTiQ8LOMCsDbJGwNxLuwXfYu7vLx8gRjVyJs8dIfN+Sk+dr8BmbVDPivUBlAFDZhhMWm kgmd2EaUsOhc9qz4+yxVEOnkWXdaeT9n4YfdhdBg/PYDHX/djJogMtGDtq+/O8ubc+o4/DJgzPc TS5qDkrlEMki4yxGQpk7zodx7Jhcsz584/WNNV/3zq0Ipsu+11nl2nSMuF4= X-Google-Smtp-Source: AGHT+IHNRDrIGY84WUUkBTT6iifj/Wc19+96QDKrhrvMwFfcVHROjar/m0bBTLJ4og3rpYFs8jAMAeYMaeReN9hOcFM= X-Received: by 2002:a05:690c:fd5:b0:786:8ce9:3b55 with SMTP id 00721157ae682-78c33afd0b3mr18315667b3.5.1765024103716; Sat, 06 Dec 2025 04:28:23 -0800 (PST) MIME-Version: 1.0 References: <20251201093741.730884-1-kartikey406@gmail.com> In-Reply-To: From: Deepanshu Kartikey Date: Sat, 6 Dec 2025 17:58:10 +0530 X-Gm-Features: AQt7F2oUWf8gx4gkUoldxOL20pZvMkLOr_KWrlTZF23dSdsTYcSrhoG2xNIiFSU Message-ID: Subject: Re: [PATCH] mm/swapfile: validate swap offset in unuse_pte_range() To: Kairui Song Cc: akpm@linux-foundation.org, chrisl@kernel.org, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, baohua@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, YoungJun Park , syzbot+d7bc9ec4a100437aa7a2@syzkaller.appspotmail.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: BA08D14000B X-Rspamd-Server: rspam10 X-Stat-Signature: ww1no4cdkpbsxacfb5nciwwtatah9nkt X-HE-Tag: 1765024104-351805 X-HE-Meta: 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 Vq10ER/j 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000039, 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 Wed, Dec 3, 2025 at 8:24=E2=80=AFAM Kairui Song wrote= : > > If softleaf v3 has fixed the underlying issue, I can withdraw this > > patch. Or if you think a defensive sanity check still has value, I can > > update the commit message to reflect that it is defensive hardening > > rather than a fix for an active bug. > > A sanity check here is acceptable since swapoff is cold and the > overhead is hardly visible. No strong opinion on this one. Hi Kairui, Thank you for the link and clarification! I'll study Lorenzo's fix to understand the root cause better. Since you mentioned a sanity check is acceptable here, should I update the commit message to frame this as defensive hardening rather than a bug fix? Something like: mm/swapfile: add defensive bounds check in unuse_pte_range() Add a sanity check to validate the swap offset is within bounds before using it. While there is no known code path that can trigger an out-of-bounds offset, this provides defense against potential edge cases or memory corruption. The overhead is negligible since swapoff is a cold path. Thanks, Deepanshu