From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757336Ab2DTSAY (ORCPT ); Fri, 20 Apr 2012 14:00:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44702 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757305Ab2DTSAW (ORCPT ); Fri, 20 Apr 2012 14:00:22 -0400 Date: Fri, 20 Apr 2012 19:59:34 +0200 From: Oleg Nesterov To: Konstantin Khlebnikov Cc: Andrew Morton , Hugh Dickins , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Markus Trippelsdorf , KAMEZAWA Hiroyuki Subject: Re: [PATCH 1/2] mm: set task exit code before complete_vfork_done() Message-ID: <20120420175934.GA31905@redhat.com> References: <20120409200336.8368.63793.stgit@zurg> <20120412080948.26401.23572.stgit@zurg> <20120412235446.GA4815@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120412235446.GA4815@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/13, Oleg Nesterov wrote: > > Damn, Konstantin I have to admit, I'll try to find another technical > reason against mm-correctly-synchronize-rss-counters-at-exit-exec.patch > even with this fix ;) > > Most probably I am wrong, but it looks overcomplicated. Somehow I > dislike irrationally the fact you moved mm_release() from exit_mm(). And perhaps you can help me to discredit your patch? It turns out, I do not really understand this code in do_exit: /* sync mm's RSS info before statistics gathering */ if (tsk->mm) sync_mm_rss(tsk->mm); Which "statistics gathering" ? Probably I missed something, but after the quick grep it seems to me that this is only needed for taskstats_exit()->xacct_add_tsk(). So why we can't simply add sync_mm_rss() into xacct_add_tsk() ? Yes, this way we do not "account" put_user(clear_child_tid) but I think we do not care. IOW, what do you think about the trivial patch below? Uncompiled, untested, probably incomplete. acct_update_integrals() looks suspicious too. Oleg. --- a/kernel/tsacct.c +++ b/kernel/tsacct.c @@ -91,6 +91,7 @@ void xacct_add_tsk(struct taskstats *sta stats->virtmem = p->acct_vm_mem1 * PAGE_SIZE / MB; mm = get_task_mm(p); if (mm) { + sync_mm_rss(mm); /* adjust to KB unit */ stats->hiwater_rss = get_mm_hiwater_rss(mm) * PAGE_SIZE / KB; stats->hiwater_vm = get_mm_hiwater_vm(mm) * PAGE_SIZE / KB; --- a/kernel/exit.c +++ b/kernel/exit.c @@ -643,6 +643,8 @@ static void exit_mm(struct task_struct * mm_release(tsk, mm); if (!mm) return; + + sync_mm_rss(mm); /* * Serialize with any possible pending coredump. * We must hold mmap_sem around checking core_state @@ -960,9 +962,6 @@ void do_exit(long code) preempt_count()); acct_update_integrals(tsk); - /* sync mm's RSS info before statistics gathering */ - if (tsk->mm) - sync_mm_rss(tsk->mm); group_dead = atomic_dec_and_test(&tsk->signal->live); if (group_dead) { hrtimer_cancel(&tsk->signal->real_timer); --- a/fs/exec.c +++ b/fs/exec.c @@ -823,10 +823,10 @@ static int exec_mmap(struct mm_struct *m /* Notify parent that we're no longer interested in the old VM */ tsk = current; old_mm = current->mm; - sync_mm_rss(old_mm); mm_release(tsk, old_mm); if (old_mm) { + sync_mm_rss(old_mm); /* * Make sure that if there is a core dump in progress * for the old mm, we get out and die instead of going From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx108.postini.com [74.125.245.108]) by kanga.kvack.org (Postfix) with SMTP id 7EBC06B004D for ; Fri, 20 Apr 2012 14:00:14 -0400 (EDT) Date: Fri, 20 Apr 2012 19:59:34 +0200 From: Oleg Nesterov Subject: Re: [PATCH 1/2] mm: set task exit code before complete_vfork_done() Message-ID: <20120420175934.GA31905@redhat.com> References: <20120409200336.8368.63793.stgit@zurg> <20120412080948.26401.23572.stgit@zurg> <20120412235446.GA4815@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120412235446.GA4815@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Konstantin Khlebnikov Cc: Andrew Morton , Hugh Dickins , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Markus Trippelsdorf , KAMEZAWA Hiroyuki On 04/13, Oleg Nesterov wrote: > > Damn, Konstantin I have to admit, I'll try to find another technical > reason against mm-correctly-synchronize-rss-counters-at-exit-exec.patch > even with this fix ;) > > Most probably I am wrong, but it looks overcomplicated. Somehow I > dislike irrationally the fact you moved mm_release() from exit_mm(). And perhaps you can help me to discredit your patch? It turns out, I do not really understand this code in do_exit: /* sync mm's RSS info before statistics gathering */ if (tsk->mm) sync_mm_rss(tsk->mm); Which "statistics gathering" ? Probably I missed something, but after the quick grep it seems to me that this is only needed for taskstats_exit()->xacct_add_tsk(). So why we can't simply add sync_mm_rss() into xacct_add_tsk() ? Yes, this way we do not "account" put_user(clear_child_tid) but I think we do not care. IOW, what do you think about the trivial patch below? Uncompiled, untested, probably incomplete. acct_update_integrals() looks suspicious too. Oleg. --- a/kernel/tsacct.c +++ b/kernel/tsacct.c @@ -91,6 +91,7 @@ void xacct_add_tsk(struct taskstats *sta stats->virtmem = p->acct_vm_mem1 * PAGE_SIZE / MB; mm = get_task_mm(p); if (mm) { + sync_mm_rss(mm); /* adjust to KB unit */ stats->hiwater_rss = get_mm_hiwater_rss(mm) * PAGE_SIZE / KB; stats->hiwater_vm = get_mm_hiwater_vm(mm) * PAGE_SIZE / KB; --- a/kernel/exit.c +++ b/kernel/exit.c @@ -643,6 +643,8 @@ static void exit_mm(struct task_struct * mm_release(tsk, mm); if (!mm) return; + + sync_mm_rss(mm); /* * Serialize with any possible pending coredump. * We must hold mmap_sem around checking core_state @@ -960,9 +962,6 @@ void do_exit(long code) preempt_count()); acct_update_integrals(tsk); - /* sync mm's RSS info before statistics gathering */ - if (tsk->mm) - sync_mm_rss(tsk->mm); group_dead = atomic_dec_and_test(&tsk->signal->live); if (group_dead) { hrtimer_cancel(&tsk->signal->real_timer); --- a/fs/exec.c +++ b/fs/exec.c @@ -823,10 +823,10 @@ static int exec_mmap(struct mm_struct *m /* Notify parent that we're no longer interested in the old VM */ tsk = current; old_mm = current->mm; - sync_mm_rss(old_mm); mm_release(tsk, old_mm); if (old_mm) { + sync_mm_rss(old_mm); /* * Make sure that if there is a core dump in progress * for the old mm, we get out and die instead of going -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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