From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 5FAD76B0038 for ; Mon, 26 Dec 2016 06:41:25 -0500 (EST) Received: by mail-pf0-f199.google.com with SMTP id 17so482120009pfy.2 for ; Mon, 26 Dec 2016 03:41:25 -0800 (PST) Received: from mail-pg0-x243.google.com (mail-pg0-x243.google.com. [2607:f8b0:400e:c05::243]) by mx.google.com with ESMTPS id k74si16607867pfj.185.2016.12.26.03.41.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 26 Dec 2016 03:41:24 -0800 (PST) Received: by mail-pg0-x243.google.com with SMTP id g1so9078871pgn.0 for ; Mon, 26 Dec 2016 03:41:24 -0800 (PST) Date: Mon, 26 Dec 2016 20:41:06 +0900 From: Sergey Senozhatsky Subject: Re: [PATCH] mm/page_alloc: Wait for oom_lock before retrying. Message-ID: <20161226114106.GB515@tigerII.localdomain> References: <20161220153948.GA575@tigerII.localdomain> <201612221927.BGE30207.OSFJMFLFOHQtOV@I-love.SAKURA.ne.jp> <20161222134250.GE413@tigerII.localdomain> <201612222301.AFG57832.QOFMSVFOJHLOtF@I-love.SAKURA.ne.jp> <20161222140930.GF413@tigerII.localdomain> <201612261954.FJE69201.OFLVtFJSQFOHMO@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201612261954.FJE69201.OFLVtFJSQFOHMO@I-love.SAKURA.ne.jp> Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: sergey.senozhatsky@gmail.com, mhocko@suse.com, linux-mm@kvack.org, pmladek@suse.cz On (12/26/16 19:54), Tetsuo Handa wrote: > I tried these 9 patches. Generally OK. > > Although there is still "schedule_timeout_killable() lockup with oom_lock held" > problem, async-printk patches help avoiding "printk() lockup with oom_lock held" > problem. Thank you. > > Three comments from me. > > (1) Messages from e.g. SysRq-b is not waited for sent to consoles. > "SysRq : Resetting" line is needed as a note that I gave up waiting. > > (2) Messages from e.g. SysRq-t should be sent to consoles synchronously? > "echo t > /proc/sysrq-trigger" case can use asynchronous printing. > But since ALT-SysRq-T sequence from keyboard may be used when scheduler > is not responding, it might be better to use synchronous printing. > (Or define a magic key sequence to toggle synchronous/asynchronous?) it's really hard to tell if the message comes from sysrq or from somewhere else. the current approach -- switch to *always* sync printk once we see the first LOGLEVEL_EMERG message. so you can add printk(LOGLEVEL_EMERG "sysrq-t\n"); for example, and printk will switch to sync mode. sync mode, is might be a bit dangerous though, since we printk from IRQ. -ss -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org