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Sun, 8 Mar 2020 09:59:05 +0000 (GMT) Subject: Re: [PATCH] mm: mmap: show vm_unmapped_area error log To: Matthew Wilcox , Andrew Morton Cc: walken@google.com, bp@suse.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, jaewon31.kim@gmail.com From: Jaewon Kim Message-ID: <5E64C1D7.3000208@samsung.com> Date: Sun, 8 Mar 2020 18:58:47 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <20200308015802.GD31215@bombadil.infradead.org> X-Brightmail-Tracker: H4sIAAAAAAAAA01Se0hTcRTu193uruHiOs0OFrluD9psteucXsVZUMQgIaEH6R/abbtt2l7t bpZGZCnaQ7OkIF+0ip74gK3HNCOzsEywIEKK7EUEJVaahWVq2+4k//vOd76P853z+xGY7Bwe R+TbXJzTxloofI7o1gOFSjV435irbmmLZRpam3DmVLWCOe6rRczz9gacedM0JWYmaw4w42MN +FqJvq1uQKL3eN1631Wl3jtSI9E/Pjsu0vt69+t/eBdlSXIs6WaONXJOOWcz2I35NpOO2rg5 b12eNllNq+hUJoWS21grp6PWZ2apNuRbAlkoeSFrcQeoLJbnqdUZ6U6728XJzXbepaM4h9Hi oNWOVTxr5d020yqD3ZpGq9WJ2oByh8U80F0rcjyJ2NfdHFWCBiTHUAQBZBL0TlycfQzNIWSk H4F30C8WihEEFR/vh4tfCM4+rRZPW4bHOnChcRfB25ZKPNiQkUMIpry7gjiazIDuMw9Dhhhy K/j7mgMagsBIK1R0W4M0TibAN09NSCIllXD+4QlREIvIpdBbdTwUbx65HfyNw0jQREFP7ceQ JoJMh3cfXobGYmQ8lN6sx4J5gOzH4fW70+Hd1kN9fWcYR8OXRzfCOA4+V5dLBEMpgqFaHxKK MgQD3iokqDRQVfkME1IroLV9tUAvhrbxRiRMngtff1aKgxIgpXCkXCZIlkPZp5/hYy2EiclP YawHv+9J+HDlGJSWT2AnkbxuxnJ1Mxaq+z/Zg7DrKJZz8FYTx9OOpJkv7EWhz6lk/KijL7ML kQSiIqU7+gy5MjFbyBdZuxAQGBUjPaQMUFIjW1TMOe15TreF47uQNnDvU1jcPIM98NVtrjxa m6jRaJik5JRkrYaaL32frciVkSbWxe3mOAfnnPbNJiLiStCygysUTfLYS9lRc2P2eEqTc1S3 70S+PHrl/ciCTj6z+GKkaXgiLSfh3vcfhdcK1s3am/p5y5IC8/V+itkpGsWe0Wm3ZI/XpLVL cxN6qs589e3ZtFU3TsevTLQb3hb4dZe3XRjtXzP0m/c89RtftFanjvREv7p2clQ1WHy40jv5 N/sPJeLNLK3EnDz7D5wYmhuyAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrHLMWRmVeSWpSXmKPExsWy7bCSvO7LgylxBpfbbSzmrF/DZjGxX9Oi e/NMRovLu+awWdxb85/V4t+kWovfP+awObB77Jx1l91jwaZSj80rtDw2fZrE7nFixm8Wj82n qz0+b5ILYI/isklJzcksSy3St0vgyrh7bCZLwSnOimNrBRsY77J3MXJySAiYSHz8sYeti5GL Q0hgN6PEo+9v2SASMhJvzj9l6WLkALKFJQ4fLoaoec0oMXXGJGaQGmEBO4ljU4+wgtgiAqES V988YYEoamOWeHD5LFiCWSBX4t2zaWBD2QS0Jd4vmAQW5xXQklh4pI8FxGYRUJE43dsNdpGo QITE6nXXmCFqBCVOznwCVsMpYCPx4NFNNpCDmAXUJdbPE4IYLy/RvHU28wRGwVlIOmYhVM1C UrWAkXkVo2RqQXFuem6xYYFRXmq5XnFibnFpXrpecn7uJkZwLGhp7WA8cSL+EKMAB6MSD++O C8lxQqyJZcWVuYcYJTiYlUR4G7WAQrwpiZVVqUX58UWlOanFhxilOViUxHnl849FCgmkJ5ak ZqemFqQWwWSZODilGhg9pzh267I6rH83XfNU2iq5tOkOutoNLZ5Vs9SEdeRWVcxnyapiehJ/ tsOgM2KqeVjD4jz+2ZOnbDc1kd3/t+G9grx9Meu2Z0mq3g6VpoG2TXOK0ueJ7fm048ydk/Pe 1ypPPPLixJLzVXqXL+3r1gioYcxxTIhdcSBJulf8pMbR8vS8Wd1275RYijMSDbWYi4oTAfk2 bKaBAgAA X-CMS-MailID: 20200308095906epcas1p150fec0fb5b86907b09be9104f7171f12 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: SVC_REQ_APPROVE CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20200304030211epcas1p4da8cb569947aefb3aad1da039aaabce4 References: <20200304030206.1706-1-jaewon31.kim@samsung.com> <5E605749.9050509@samsung.com> <20200305202443.8de3598558336b1d75afbba7@linux-foundation.org> <5E61EAB6.5080609@samsung.com> <20200307154744.acd523831b45efa8d0fc1dfa@linux-foundation.org> <20200308015802.GD31215@bombadil.infradead.org> Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2020=EB=85=84 03=EC=9B=94 08=EC=9D=BC 10:58, Matthew Wilcox wrote: > On Sat, Mar 07, 2020 at 03:47:44PM -0800, Andrew Morton wrote: >> On Fri, 6 Mar 2020 15:16:22 +0900 Jaewon Kim wrote: >>> Even on 64 bit kernel, the mmap failure can happen for a 32 bit task. >>> Virtual memory space shortage of a task on mmap is reported to usersp= ace >>> as -ENOMEM. It can be confused as physical memory shortage of overall >>> system. > But userspace can trigger this printk. We don't usually allow printks > under those circumstances, even ratelimited. Hello thank you your comment. Yes, userspace can trigger printk, but this was useful for to know why a userspace task was crashed. There seems to be still many userspace applications which did not check error of mmap and access invalid address= . Additionally in my AARCH64 Android environment, display driver tries to get userspace address to map its display memory. The display driver report -ENOMEM from vm_unmapped_area and but also from GPU related address space. Please let me know your comment again if this debug is now allowed in that userspace triggered perspective. I may change to pr_debug or drop this change. Thank you > >