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Wysocki" Date: Thu, 14 Mar 2024 16:55:31 +0100 Message-ID: Subject: Re: [PATCH] x86/pm: Fix false positive kmemleak report in msr_build_context(). To: Dave Hansen Cc: Anton Altaparmakov , "Rafael J . Wysocki" , Pavel Machek , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , Chen Yu , Pawan Gupta , Catalin Marinas , linux-mm@kvack.org, Matthieu Baerts , Mat Martineau , "Rafael J . Wysocki" , Ingo Molnar , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: uo4gaxrhjo47a69x9otx6uu8sguoak7o X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 6A04F40012 X-Rspam-User: X-HE-Tag: 1710431743-608772 X-HE-Meta: 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 UTTVRZch goY5dzgdkn182q4soJV6huDfGjq33CiX7Ur3F2o21K3YMPveMfgaVq9s8awHYxm/8y22MLnPcGlJO/TCIA13CssKmp2Fy54QRRS4SMlKBs6BeRZSlEi1ldRTvtxFNor2tyDFTuGEZiBV/uJ6eGzXerm7UHAsKIlWPgHIxZ6lwKMXpwhS70rKlKbqeQC/gpXvPwl8PX09NwCfRzOhMwTY2/Sj/i1zP4w7qRCCe9DfKphvUle1tFxtDLxhU6Fu0Cgq/sh6nrclJ4oExTmMJ0iL4WzBdYo2X2/4wY3H2KXbaq3Xw1i09wwHT2B5EY4ml3uJRFzlFq2KGAVzSbiVQFwGNto83n50Ge4h9nCYUlYv3e2J/Azofmy+iW4MFwIPlBbOi/JzMg6xzKqpwYuVKpKf054Yocnk1XAgw/hOa 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: On Thu, Mar 14, 2024 at 4:05=E2=80=AFPM Dave Hansen = wrote: > > On 3/14/24 07:26, Anton Altaparmakov wrote: > > /* image of the saved processor state */ > > struct saved_context { > > - /* > > - * On x86_32, all segment registers except gs are saved at kernel > > - * entry in pt_regs. > > - */ > > - u16 gs; > > unsigned long cr0, cr2, cr3, cr4; > > u64 misc_enable; > > struct saved_msrs saved_msrs; > > @@ -27,6 +22,11 @@ struct saved_context { > > unsigned long tr; > > unsigned long safety; > > unsigned long return_address; > > + /* > > + * On x86_32, all segment registers except gs are saved at kernel > > + * entry in pt_regs. > > + */ > > + u16 gs; > > bool misc_enable_saved; > > } __attribute__((packed)); > > Isn't this just kinda poking at the symptoms? This seems to be > basically the exact same bug as b0b592cf08, just with a different source > of unaligned structure members. > > There's nothing to keep folks from reintroducing these kinds of issues > and evidently no way to detect when they happen without lengthy reproduce= rs. This change is fine with me FWIW, but I agree that making it for kmemleak reasons feels kind of misguided.