From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E363CC433FF for ; Tue, 30 Jul 2019 08:03:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BF7B5206A2 for ; Tue, 30 Jul 2019 08:03:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729999AbfG3ID6 (ORCPT ); Tue, 30 Jul 2019 04:03:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33776 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729810AbfG3ID6 (ORCPT ); Tue, 30 Jul 2019 04:03:58 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5026330C5843; Tue, 30 Jul 2019 08:03:57 +0000 (UTC) Received: from [10.72.12.185] (ovpn-12-185.pek2.redhat.com [10.72.12.185]) by smtp.corp.redhat.com (Postfix) with ESMTP id D89B65D6A5; Tue, 30 Jul 2019 08:03:46 +0000 (UTC) Subject: Re: WARNING in __mmdrop From: Jason Wang To: "Michael S. Tsirkin" Cc: syzbot , aarcange@redhat.com, akpm@linux-foundation.org, christian@brauner.io, davem@davemloft.net, ebiederm@xmission.com, elena.reshetova@intel.com, guro@fb.com, hch@infradead.org, james.bottomley@hansenpartnership.com, jglisse@redhat.com, keescook@chromium.org, ldv@altlinux.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-parisc@vger.kernel.org, luto@amacapital.net, mhocko@suse.com, mingo@kernel.org, namit@vmware.com, peterz@infradead.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk, wad@chromium.org References: <11802a8a-ce41-f427-63d5-b6a4cf96bb3f@redhat.com> <20190726074644-mutt-send-email-mst@kernel.org> <5cc94f15-b229-a290-55f3-8295266edb2b@redhat.com> <20190726082837-mutt-send-email-mst@kernel.org> <20190726094756-mutt-send-email-mst@kernel.org> <0792ee09-b4b7-673c-2251-e5e0ce0fbe32@redhat.com> <20190729045127-mutt-send-email-mst@kernel.org> <4d43c094-44ed-dbac-b863-48fc3d754378@redhat.com> <20190729104028-mutt-send-email-mst@kernel.org> <96b1d67c-3a8d-1224-e9f0-5f7725a3dc10@redhat.com> Message-ID: Date: Tue, 30 Jul 2019 16:03:45 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <96b1d67c-3a8d-1224-e9f0-5f7725a3dc10@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Tue, 30 Jul 2019 08:03:57 +0000 (UTC) Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On 2019/7/30 下午3:44, Jason Wang wrote: >>> >>> } >> Looks good but I'd like to think of a strategy/existing lock that let us >> block properly as opposed to spinning, that would be more friendly to >> e.g. the realtime patch. > > > Does it make sense to disable preemption in the critical section? Then > we don't need to block and we have a deterministic time spent on > memory accssors? Ok, touching preempt counter seems a little bit expensive in the fast path. Will try for blocking. Thanks From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E31EDC433FF for ; Tue, 30 Jul 2019 08:04:13 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B5A9A206A2 for ; Tue, 30 Jul 2019 08:04:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="d6qHvuw7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B5A9A206A2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:References: To:From:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=cHOvrw1z/OKVvp//C9+tqEJrMfxgnWzobDfjROsKo4w=; b=d6qHvuw7o81BgdNcR0W2aSf5H bw5Dk2pbiVgjRfYUXUEL6LGGIbJvp3haXzpxxXBrguDYDvkPtScURFyXGwgVpLpCeTLcylQ1op99C gNUp7/KjrsPS+/G9WFE4lFqVIxCr6OwukJ7phybsq3sRQo4NKPBpKPsJmomRPl+BZe/wJPjFNRecc GDKregkq7BxIHi8MwiVRsLKxoakvq/0oo1MF2fZeyJaIDMI4ZFOXKaiC+JVe7xwB6858mSCQM8GZQ 0czTo0xDGuPDWRqIbBVhIqUGxWN+Va0/ALVBTtt4OrdS/svPenrZaP3E3v4/Bbkq8NRGCqK7LXowD 7Es7uWCgQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hsN73-0001Dg-E7; Tue, 30 Jul 2019 08:04:01 +0000 Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hsN70-0001DM-DS for linux-arm-kernel@lists.infradead.org; Tue, 30 Jul 2019 08:03:59 +0000 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5026330C5843; Tue, 30 Jul 2019 08:03:57 +0000 (UTC) Received: from [10.72.12.185] (ovpn-12-185.pek2.redhat.com [10.72.12.185]) by smtp.corp.redhat.com (Postfix) with ESMTP id D89B65D6A5; Tue, 30 Jul 2019 08:03:46 +0000 (UTC) Subject: Re: WARNING in __mmdrop From: Jason Wang To: "Michael S. Tsirkin" References: <11802a8a-ce41-f427-63d5-b6a4cf96bb3f@redhat.com> <20190726074644-mutt-send-email-mst@kernel.org> <5cc94f15-b229-a290-55f3-8295266edb2b@redhat.com> <20190726082837-mutt-send-email-mst@kernel.org> <20190726094756-mutt-send-email-mst@kernel.org> <0792ee09-b4b7-673c-2251-e5e0ce0fbe32@redhat.com> <20190729045127-mutt-send-email-mst@kernel.org> <4d43c094-44ed-dbac-b863-48fc3d754378@redhat.com> <20190729104028-mutt-send-email-mst@kernel.org> <96b1d67c-3a8d-1224-e9f0-5f7725a3dc10@redhat.com> Message-ID: Date: Tue, 30 Jul 2019 16:03:45 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <96b1d67c-3a8d-1224-e9f0-5f7725a3dc10@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Tue, 30 Jul 2019 08:03:57 +0000 (UTC) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190730_010358_475065_3AC3CCEF X-CRM114-Status: GOOD ( 12.74 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mhocko@suse.com, peterz@infradead.org, ldv@altlinux.org, james.bottomley@hansenpartnership.com, linux-mm@kvack.org, namit@vmware.com, mingo@kernel.org, elena.reshetova@intel.com, keescook@chromium.org, aarcange@redhat.com, davem@davemloft.net, hch@infradead.org, christian@brauner.io, syzbot , syzkaller-bugs@googlegroups.com, jglisse@redhat.com, viro@zeniv.linux.org.uk, linux-arm-kernel@lists.infradead.org, wad@chromium.org, linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org, luto@amacapital.net, ebiederm@xmission.com, akpm@linux-foundation.org, guro@fb.com Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Ck9uIDIwMTkvNy8zMCDkuIvljYgzOjQ0LCBKYXNvbiBXYW5nIHdyb3RlOgo+Pj4KPj4+IH0KPj4g TG9va3MgZ29vZCBidXQgSSdkIGxpa2UgdG8gdGhpbmsgb2YgYSBzdHJhdGVneS9leGlzdGluZyBs b2NrIHRoYXQgbGV0IHVzCj4+IGJsb2NrIHByb3Blcmx5IGFzIG9wcG9zZWQgdG8gc3Bpbm5pbmcs IHRoYXQgd291bGQgYmUgbW9yZSBmcmllbmRseSB0bwo+PiBlLmcuIHRoZSByZWFsdGltZSBwYXRj aC4KPgo+Cj4gRG9lcyBpdCBtYWtlIHNlbnNlIHRvIGRpc2FibGUgcHJlZW1wdGlvbiBpbiB0aGUg Y3JpdGljYWwgc2VjdGlvbj8gVGhlbiAKPiB3ZSBkb24ndCBuZWVkIHRvIGJsb2NrIGFuZCB3ZSBo YXZlIGEgZGV0ZXJtaW5pc3RpYyB0aW1lIHNwZW50IG9uIAo+IG1lbW9yeSBhY2Nzc29ycz8KCgpP aywgdG91Y2hpbmcgcHJlZW1wdCBjb3VudGVyIHNlZW1zIGEgbGl0dGxlIGJpdCBleHBlbnNpdmUg aW4gdGhlIGZhc3QgCnBhdGguIFdpbGwgdHJ5IGZvciBibG9ja2luZy4KClRoYW5rcwoKCl9fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCmxpbnV4LWFybS1rZXJu ZWwgbWFpbGluZyBsaXN0CmxpbnV4LWFybS1rZXJuZWxAbGlzdHMuaW5mcmFkZWFkLm9yZwpodHRw Oi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2xpbnV4LWFybS1rZXJuZWwK