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[109.81.83.72]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a838394645dsm606157966b.144.2024.08.19.00.51.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Aug 2024 00:51:51 -0700 (PDT) Date: Mon, 19 Aug 2024 09:51:50 +0200 From: Michal Hocko To: Yafang Shao Cc: Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org, 42.hyeyoo@gmail.com, cl@linux.com, hailong.liu@oppo.com, hch@infradead.org, iamjoonsoo.kim@lge.com, penberg@kernel.org, rientjes@google.com, roman.gushchin@linux.dev, torvalds@linux-foundation.org, urezki@gmail.com, v-songbaohua@oppo.com, vbabka@suse.cz, virtualization@lists.linux.dev, Lorenzo Stoakes , Kees Cook , Eugenio =?iso-8859-1?Q?P=E9rez?= , Jason Wang , Maxime Coquelin , "Michael S. Tsirkin" , Xuan Zhuo Subject: Re: [PATCH v3 4/4] mm: prohibit NULL deference exposed for unsupported non-blockable __GFP_NOFAIL Message-ID: References: <20240817062449.21164-1-21cnbao@gmail.com> <20240817062449.21164-5-21cnbao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7C18DC000F X-Stat-Signature: k9u5whf9jjh57pxbnum7ztrs4oitsag7 X-HE-Tag: 1724053913-401331 X-HE-Meta: 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 15A8ZBHW 0Chs9YErXD2k2UV+DCHfEe0tEhsRWDFMMrMj8X4dWYzZ86qwlW4LrhLlWKSam4ph3fdVQuzRt4hysSTwyXtTGx0bK5bz/ErolQQC1PyGuUZfOXQV6Mha2T4lvSilCD3Awgzzy5tQ7QGfXl2dN/MkLVjmcmNqHQmEZvyY+3p+sHmwuRleb6VblLGzIBgTV9LrNXJ5BpitrYVIX7xSbx+PQwhzgtqHS972P7J9+4uUKj2DlX01B0yqQBl/FAQJe2ywqpXvuhFv4i+As02UtgEl3SEPZvArq0PLjilBMYLzij7+t2rMjDhJ2zFBweokOKLL4xFcqmLmsP5tbAw5faog+d0cFHz9SkWQwbFtRFQ0zaOVAh6tQT5TCk1pLssDCFNq/q9wUnRtA3I6qHxqnriYdmytuMg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000534, 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 Sun 18-08-24 15:07:00, Yafang Shao wrote: > That can be avoided by a simple cond_resched() if the hard lockup or > softlockup is the main issue ;) No, it cannot! cond_resched from withing an atomic context is no-no. And NOWAIT is used from withing atomic contexts. -- Michal Hocko SUSE Labs