From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f43.google.com (mail-ej1-f43.google.com [209.85.218.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9DE87158A09 for ; Mon, 19 Aug 2024 07:51:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724053915; cv=none; b=J7+kc+1Xqty0F0vK4PkK2FA53yTvnZY4Akvf0kcxTXhAQbrEXt/TIXGB84XmQb52Z9ihGIwvxnL5uWW8qSOrTjwHbnhkLVMtJzwOtKumDuyGuUhzvvePNbZjwczhIQrOAJoeZc8fAG5DpPQjLdv4m3k4wvBF8NG3foDua/ikVD0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724053915; c=relaxed/simple; bh=UGPY+1GjNPazkb7vGKIf/8zxTAAkxIiZ0PWAx6W8Doo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ilFDCgvb1JNiUcwanu+ztWm5JpZp0sOBRGT1uPmTVVY7H9SD+MBVx3QQQeqIbgFDdMnz3IRTOk3LN4b19/7qXxIDRTpff4mfXVhbK2WqavUfJ1pq9kGyO+HT7szHP204EEPtg4CUhIIoSTfrvR9zh50O0/kFt6sjKLqPYYDtZpQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=Z6Cgnq38; arc=none smtp.client-ip=209.85.218.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="Z6Cgnq38" Received: by mail-ej1-f43.google.com with SMTP id a640c23a62f3a-a7aada2358fso781314966b.0 for ; Mon, 19 Aug 2024 00:51:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1724053912; x=1724658712; darn=lists.linux.dev; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=hfxCbJ0oz0BjnXe6UDD49N8FalEMneDsX4L511QNvzo=; b=Z6Cgnq38ITqApeBPn2RQqbNYVYWUbtMzYcc5GcYGgh5DXxeaI+gY6YGpKrR5ID/s/E YPV27so68ZK+j3wSjl63yJODG+8FotcJ5GL5K5ko0m2vIcQQrWOwFV8E0nSil5sny5tg 3E9paM4UMNMEzlLniShC5u7ne5kqM7uzapfnnYgwrLxIz7zlTyUDI36u66dXs7M2q+JS aZ7ogLu7flnk0KYs/icUxsbAbMH9D4ZtdBpFJ3UHP0BpNaFSazus9mJSPKq6KU2oNcKh 4k1uOSTafIMVNlh45N7mcyRW3HwOk0MxGqY53e15ojBPZxPFCX14TA4uW79m1p7VwTxX whbg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724053912; x=1724658712; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=hfxCbJ0oz0BjnXe6UDD49N8FalEMneDsX4L511QNvzo=; b=IJ2lHZkvzLEAKN7WbMbowsIr/P44LlXfzFvqg0ASzHcLiSfOFefMjIyv/GrtZjy6eZ m/1WXA8S60J6OHh8lOpmwcOAhzgqDUrtAprHplFmTDZ8rAl9l9/Dmzrv9tvIhEcDZFD6 YJE8RRTPYHSkN6bhGXjiR9xT+J+MF+xFF6yUBAulU1vlYJY0sYtpCU9G5KZ/qaEq2J57 zpsm9T81j8FazHJjIwLSsBCrXUzlqG5imtsD61jGfHqplIvoAKTBHU//FmzoA7vs3a2x 3fEryFmXdPSI7zYFWtEmaPqhMvvK/oq/OQWSgLRnB1vyhsXmzbSLusloM24bMoeXzcFy IyQQ== X-Forwarded-Encrypted: i=1; AJvYcCXoPZjZ8qglJWcmn+3ycYHt0o42uHhl84Yq5qltTftI5Q/+yu3VmvLKePaB0ZsB/8HaGTgrM48o2h68E0jASFhuVf7Qc/xQl7aZZGKm7yA= X-Gm-Message-State: AOJu0YyaIbd++R7MCd0n0nhAiJlDU7YvOWMI/naHwuLoMMCokgTlasYa gT1LuqOCjXn4BydDDk+Pvh7JpMpIQeOxjtaDe+Ocs4uhlLFJvCyi0jhhHW3hZ7c= X-Google-Smtp-Source: AGHT+IHSUcqLb1+f1zcdTbLwA8OIHGmuo7k2hZNR4LhJgHm31w5qRPe0QyF+uSgNCinoLWosF7erZA== X-Received: by 2002:a17:907:f765:b0:a73:9037:fdf5 with SMTP id a640c23a62f3a-a8394d6a35fmr1022877966b.6.1724053911765; Mon, 19 Aug 2024 00:51:51 -0700 (PDT) Received: from localhost (109-81-83-72.rct.o2.cz. [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> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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