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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89D80C28D13 for ; Mon, 22 Aug 2022 23:00:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 075946B0073; Mon, 22 Aug 2022 19:00:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 025046B0074; Mon, 22 Aug 2022 19:00:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E075D8D0001; Mon, 22 Aug 2022 19:00:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id CE32E6B0073 for ; Mon, 22 Aug 2022 19:00:06 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id AB9AF1A1350 for ; Mon, 22 Aug 2022 23:00:06 +0000 (UTC) X-FDA: 79828748412.04.5E0B4B1 Received: from mail-vs1-f45.google.com (mail-vs1-f45.google.com [209.85.217.45]) by imf28.hostedemail.com (Postfix) with ESMTP id 5A2D7C0017 for ; Mon, 22 Aug 2022 23:00:06 +0000 (UTC) Received: by mail-vs1-f45.google.com with SMTP id 190so4568765vsz.7 for ; Mon, 22 Aug 2022 16:00:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc; bh=CM+r2jDGi3Z1TY+2nDEEa9bz6Cg3yXP3SO7YhqCHkfo=; b=Fr4ZUOwdWXPMWZ0VIHwPHNgnoI5vRT/AKqrE1La5ulyUniUsetq7t6w4qi4Tj30KgQ aujMKcxmiWsb3YvpamUxbl8zMbQJJbv1lsgsyWYXtBqwUGVgpV2Ydzp1NdfAUnMkovb2 lIG66WjOS9iJKkXJLidAFbWQthLLWYlTUg7QI0vTlpePU0jcFWQoI3qBJiKJxSBBKJzI /TSaEZxLBRFc7HzsZro7nHfqq5FJdPwiaZFUIvnj9rKwwXaqHHfg2ewEb3/+WyJThfJ5 YlW5CrXOD4oDXH94xu4+GKkDslxcKAjdavOsENDv+vxICJgtGpTqmDNJuttyCBg7if6i A/8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc; bh=CM+r2jDGi3Z1TY+2nDEEa9bz6Cg3yXP3SO7YhqCHkfo=; b=w00WLE96bcGJ2vZhwAT6YgnC6WGGY7es3XW9yNz9rdPe5rAUbuJw+UNX0hro8zq4jB 6DJ3fUp8OSG4HsGC8wKlB8kvhU6UAuJcXCcuvrHfuD7WX4LaC/gpiA/MTfafnFrKdAZX M00qwaR07qQ/tY+d8GHMPxpomrY6eh1D9DXT1b5v2yd0kg41QrVMexMQeXbWGdrb6DY/ eOj2GuE/NWLdllt1Ni/PiUSvBccfO3pMw+1t+p4CSKrjYAO7IYU84pwPLx1U/vFKUons yi/xpW8kKTBfCBVQihHr/G4seFHuJb0gwpDJTegtoWazCzkKL00NiInvLUkFdyePfT/Q N17g== X-Gm-Message-State: ACgBeo229NtREniJ3xmaXpMt1NYc/FqrZrGRg+Jgg+F9Mk32Umet5QMG 6YbpBWZ9AAvnXsTJqp6ElFFYSfrX2bGZXVQnOOTmyA== X-Google-Smtp-Source: AA6agR4ntjaDOEyCR2SDMeJVOZxMHCydD8GIIAaP1VehTb6mhepvnStH8hXJl00Zruvm8pbCQA7Bu0zLne8+bUujE48= X-Received: by 2002:a67:b009:0:b0:38a:e0f2:4108 with SMTP id z9-20020a67b009000000b0038ae0f24108mr8469258vse.9.1661209205446; Mon, 22 Aug 2022 16:00:05 -0700 (PDT) MIME-Version: 1.0 References: <20220531223100.510392-1-surenb@google.com> <20220531223100.510392-2-surenb@google.com> <20220822152119.96d40c884078229ee3e6b25e@linux-foundation.org> <20220822154822.366a9e4527b748cf99d98637@linux-foundation.org> In-Reply-To: <20220822154822.366a9e4527b748cf99d98637@linux-foundation.org> From: Yu Zhao Date: Mon, 22 Aug 2022 16:59:29 -0600 Message-ID: Subject: Re: [PATCH RESEND v2 2/2] mm: delete unused MMF_OOM_VICTIM flag To: Andrew Morton Cc: Suren Baghdasaryan , Michal Hocko , David Rientjes , Matthew Wilcox , Johannes Weiner , Roman Gushchin , Minchan Kim , "Kirill A . Shutemov" , Andrea Arcangeli , brauner@kernel.org, hch@infradead.org, oleg@redhat.com, David Hildenbrand , Jann Horn , Shakeel Butt , Peter Xu , John Hubbard , shuah@kernel.org, linux-kernel , Linux-MM , linux-kselftest@vger.kernel.org, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1661209206; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=CM+r2jDGi3Z1TY+2nDEEa9bz6Cg3yXP3SO7YhqCHkfo=; b=m4RTiEfPvI7JfbTlyBE9YpiXDYdAaKiVCjMlq58Sy7kuRV1kaejjCjaNH7jfY+qN1VjZr9 RX4NIr+6f0jvv+Wg4+v8eX3peHIi+XfbNpIDI0X7IUmZDHaHeNa4l18NmYwc2Fcbp1SUjL ow3s0GFPl87SU25M3alOH6Qd5Px3mPM= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Fr4ZUOwd; spf=pass (imf28.hostedemail.com: domain of yuzhao@google.com designates 209.85.217.45 as permitted sender) smtp.mailfrom=yuzhao@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1661209206; a=rsa-sha256; cv=none; b=m0DmDJYYMdJgVogwAVOEHa9cbbPRIB0rydbVSigN+JheXTGuxR2fxSF9woCnN0cTjiRJdD 8179jO1GXqIbg/2sS4cC2qsBrr0lP5H+pAxI93pwOs4U/2BbegM8l0cC/EG8NlDDByqjpr rB6tuvI71pODX7u2n7JGkq2CITeKz4g= X-Stat-Signature: bqryikgbmwzeu7pcsgkgkdnuzj7o8rx6 Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Fr4ZUOwd; spf=pass (imf28.hostedemail.com: domain of yuzhao@google.com designates 209.85.217.45 as permitted sender) smtp.mailfrom=yuzhao@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 5A2D7C0017 X-Rspam-User: X-HE-Tag: 1661209206-867757 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Aug 22, 2022 at 4:48 PM Andrew Morton wrote: > > On Mon, 22 Aug 2022 16:33:51 -0600 Yu Zhao wrote: > > > > --- a/mm/vmscan.c~mm-delete-unused-mmf_oom_victim-flag-fix > > > +++ a/mm/vmscan.c > > > @@ -3429,9 +3429,6 @@ static bool should_skip_mm(struct mm_str > > > if (size < MIN_LRU_BATCH) > > > return true; > > > > > > - if (mm_is_oom_victim(mm)) > > > - return true; > > > - > > > return !mmget_not_zero(mm); > > > } > > > > > > @@ -4127,9 +4124,6 @@ restart: > > > > > > walk_pmd_range(&val, addr, next, args); > > > > > > - if (mm_is_oom_victim(args->mm)) > > > - return 1; > > > - > > > /* a racy check to curtail the waiting time */ > > > if (wq_has_sleeper(&walk->lruvec->mm_state.wait)) > > > return 1; > > > _ > > > > > > Please confirm? > > > > LGTM. The deleted checks are not about correctness. > > OK, for now. > > > I've queued > > > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -3402,7 +3402,7 @@ static bool should_skip_mm(struct mm_struct *mm, > > struct lru_gen_mm_walk *walk) > > if (size < MIN_LRU_BATCH) > > return true; > > > > - if (mm_is_oom_victim(mm)) > > + if (test_bit(MMF_OOM_REAP_QUEUED, &mm->flags)) > > return true; > > > > return !mmget_not_zero(mm); > > @@ -4109,7 +4109,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned > > long start, unsigned long end, > > > > walk_pmd_range(&val, addr, next, args); > > > > - if (mm_is_oom_victim(args->mm)) > > + if (test_bit(MMF_OOM_REAP_QUEUED, &args->mm->flags)) > > return 1; > > > > /* a racy check to curtail the waiting time */ > > Oh. Why? What does this change do? The MMF_OOM_REAP_QUEUED flag is similar to the deleted MMF_OOM_VICTIM flag, but it's set at a later stage during an OOM kill. When either is set, the OOM reaper is probably already freeing the memory of this mm_struct, or at least it's going to. So there is no need to dwell on it in the reclaim path, hence not about correctness.