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AJvYcCVvHrgK3PfiTA+RpKDVyoMe+cOd4Yu3kk646cUu5jIsyLvnHTezEIR1Mw4GNN3rvBqVTDqbRSqY6A==@kvack.org X-Gm-Message-State: AOJu0Yy1+DQpfw1uKM7FaY9hBhWYUAVM4Q/xgf6U84gJEmMvxdSlXrg0 Ozk3SJmXxm7nKkFgiABdBjaHZVef0bTBw+mh/jQ5z6HGzQl29YgSjtLpfpA7rbq8N3twmHZ8U8p ON9w32Pzik8IES/0LI2J062y5gsQ= X-Google-Smtp-Source: AGHT+IE0WQ0NmOhk617CPniN3Q5Ev3kxPSUYvNkyL6aiheUQ6qDeRZnMU/o6VRn2ThWI6M/aNObwFC9YOCfv7w993BA= X-Received: by 2002:a17:903:22ca:b0:21c:fb6:7c3c with SMTP id d9443c01a7336-22e5ea78834mr91634215ad.17.1746690958567; Thu, 08 May 2025 00:55:58 -0700 (PDT) MIME-Version: 1.0 References: <20250507142552.9446-1-aha310510@gmail.com> <20250507153325.48726051dbbff4f3936a83ff@linux-foundation.org> In-Reply-To: From: Ozgur Kara Date: Thu, 8 May 2025 07:56:00 +0000 X-Gmail-Original-Message-ID: X-Gm-Features: ATxdqUGDygGB01JmmID4n9NBdwwuJ-xu2d0184zhFq2fVSzhlR3fGQyrw7etQsU Message-ID: <01100196aee4edec-7bb15b82-c37f-4a2b-a7df-dfbbb2e9e6e0-000000@eu-north-1.amazonses.com> Subject: Re: [PATCH v3] mm/vmalloc: fix data race in show_numa_info() To: Jeongjun Park Cc: Andrew Morton , urezki@gmail.com, edumazet@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Feedback-ID: ::1.eu-north-1.jZlAFvO9+f8tc21Z4t7ANdAU3Nw/ALd5VHiFFAqIVOg=:AmazonSES X-SES-Outgoing: 2025.05.08-23.251.240.11 X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: A9F12180016 X-Stat-Signature: f1q95r9cn8ef99u1qm1j8r35ffxmyupk X-HE-Tag: 1746690962-307510 X-HE-Meta: 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 wB8bSg/S /UDTfghLi1eVnS5JxzgezesyzTavn1RyoyZStNmZaR1He/PTTV6Jne+9uEojWVzReSDUF1UBuSw5C9YCA3ZiIWovFvUIsOeN9FnLJVzZzPl9nGhEv5A3hs1rWi4XLA6e6ia8c6iEkIbaJvykFCqrzKw9pIT53ZBfLIYzaq0yrJV/JoBjhUEozQHZxP57B2/WOpso3W6V0ahEcJ8OfMTXlKl35HxVMkHCHEUX8fnct9vtqYSQlpwUQ6DvCyzDZDjSnNx4TS+2AA0ERN/sZKnR0jwNIZO21Nz0vuPcT0Eh0Ms++8U+l7fS2R3gv9bHn/EKLK7Y/9OWWpTtKKX7UWRDhJebl54FoaUU7sXsAahQdK9/JfCYgoGzk/iMUym9tyakSvu6l41s3egx50YArf0/3Y68YW8AJAc4XNsQU0oEXmlqMoinRfZPZD6Y1T+tdmEANDaSXd6AdICTbXShcrKUtVVJeml57Z5l1Pg3eMqSPfAFcpid/do8ZIE6q6JzUyrsULt20V7SlVnzml7GnVCwUDS641iYaOND/i+TGwsqN9KQUVSbmS2Rvg4RX8NjzW6gWdyRad6v9uFDOy7dccUf4wpIHcJm+H7D7/I3YAcwdB2sLtK9BeKwvky5ZujXxKc4zoLL2iuyRlTwMSjsvSbBmENpIVRCTtKRLCwlQImRmPUGa3hnWcnkua0o/4CYYu6gGkWfX6a6LUlaeMfKUK8xzYp9gT78gY2e942ph7Ct51QwWVb+DrOKBHqA7xRlkigdRZV2olDij8Mtp8ARmr8kciycogw/63pKJ+VT2 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: Jeongjun Park , 8 May 2025 Per, 07:47 tarihinde =C5=9F= unu yazd=C4=B1: > > Andrew Morton wrote: > > > > On Wed, 7 May 2025 23:25:52 +0900 Jeongjun Park = wrote: > > > > > The following data-race was found in show_numa_info(): > > > > > > ... > > > > > > > > > According to this report, there is a read/write data-race because m->= private > > > is accessible to multiple CPUs. To fix this, instead of allocating th= e heap > > > in proc_vmalloc_init() and passing the heap address to m->private, > > > show_numa_info() should allocate the heap. > > > > > > One thing to note is that show_numa_info() is called in a critical se= ction > > > of a spinlock, so it must be allocated on the heap with GFP_ATOMIC fl= ag. > > > > GFP_ATOMIC is unfortunate. Can vmalloc_info_show() allocate the > > storage outside the lock and pass that pointer into show_numa_info()? > > That way will be more efficient also, less allocating and freeing. > > > > > > That's good idea! Definitely, if you modify vmalloc_info_show() to > allocate the heap before taking the spinlock and initialize the heap > to 0 at the beginning of the loop, we don't need to use GFP_ATOMIC, > and we only need to allocate the heap once, which is much more efficient. > > I'll send you v4 patch that reflects this right away. > Hello, I think so but i'm not sure if it will work because i just thought of it as an idea because we need to check if v is null or not. Regards, Ozgur > Regards, > > Jeongjun Park > > >