From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id 154946B02B4 for ; Wed, 14 Jun 2017 21:12:09 -0400 (EDT) Received: by mail-pg0-f69.google.com with SMTP id o62so316108pga.0 for ; Wed, 14 Jun 2017 18:12:09 -0700 (PDT) Received: from mail-pg0-x22a.google.com (mail-pg0-x22a.google.com. [2607:f8b0:400e:c05::22a]) by mx.google.com with ESMTPS id s22si1100513pfk.417.2017.06.14.18.12.08 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 14 Jun 2017 18:12:08 -0700 (PDT) Received: by mail-pg0-x22a.google.com with SMTP id a70so104623pge.3 for ; Wed, 14 Jun 2017 18:12:08 -0700 (PDT) Date: Wed, 14 Jun 2017 18:12:06 -0700 (PDT) From: David Rientjes Subject: Re: Sleeping BUG in khugepaged for i586 In-Reply-To: <20170608144831.GA19903@dhcp22.suse.cz> Message-ID: References: <968ae9a9-5345-18ca-c7ce-d9beaf9f43b6@lwfinger.net> <20170605144401.5a7e62887b476f0732560fa0@linux-foundation.org> <1e883924-9766-4d2a-936c-7a49b337f9e2@lwfinger.net> <9ab81c3c-e064-66d2-6e82-fc9bac125f56@suse.cz> <20170608144831.GA19903@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Vlastimil Babka , Larry Finger , Andrew Morton , LKML , linux-mm@kvack.org On Thu, 8 Jun 2017, Michal Hocko wrote: > collapse_huge_page > pte_offset_map > kmap_atomic > kmap_atomic_prot > preempt_disable > __collapse_huge_page_copy > pte_unmap > kunmap_atomic > __kunmap_atomic > preempt_enable > > I suspect, so cond_resched seems indeed inappropriate on 32b systems. > Seems to be an issue for i386 and arm with ARM_LPAE. I'm slightly surprised we can get away with __collapse_huge_page_swapin() for VM_FAULT_RETRY, unless that hasn't been encountered yet. I think the cond_resched() in __collapse_huge_page_copy() could be done only for !in_atomic() if we choose. -- 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