From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1E6C818E77D for ; Wed, 26 Jun 2024 19:20:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719429631; cv=none; b=DvI9VlzW9tFRbgat1yJ1ZE5ewujLMGoU88lv3KSQOuGFMyH9EcEfAGiDWSsLPP2watyqOVVTbEYe7KxnP3Put+j7lqgQFIQ1U5E5TkyyR5eiRHDDb/hsH9ae0O7ajC+7rKGpTy3kMqhEYEHyD8RqI3g6Ve9dzFUM6MACCHXN5js= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719429631; c=relaxed/simple; bh=RqN9ukbTTvUIXUig4VMUAuPav7JL0OFsJimdYsCidvc=; h=Date:To:From:Subject:Message-Id; b=Kg3J8t3bNzV1d7cVpvx/Wqww7VW4CRfW0c3sgcjX2yB8GC62YMOk5WHmoCFDX1wp4W94bRR+r3vg/Hbcp4ZsLXknMzsuE1WJPurdIqH3oEu/T7EDyTJn7MxBtrEy3F0rZAgozD267rWqk92i4mwEkD7xfWGZkhpQPX+LFqodPEw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=hNI8oo6B; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="hNI8oo6B" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8757EC116B1; Wed, 26 Jun 2024 19:20:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1719429630; bh=RqN9ukbTTvUIXUig4VMUAuPav7JL0OFsJimdYsCidvc=; h=Date:To:From:Subject:From; b=hNI8oo6BlbS2m+UXlsRpnovnjjSh3krhdRTV3jWzXDKP6fY5FRSadP9d71Qs5m/FE v2Vd7I4lpCS9BV9cKKSE51IZvKaR+7MjUsUcj2BVWXwKKt9Bhd5zevETd89mODRFrR w7AjyfQQZ37FT1QWkSGYsHODRwHlt3biWa7X3kz8= Date: Wed, 26 Jun 2024 12:20:29 -0700 To: mm-commits@vger.kernel.org,willy@infradead.org,tandersen@netflix.com,mjguzik@gmail.com,mhocko@suse.com,ebiederm@xmission.com,brauner@kernel.org,axboe@kernel.dk,alexjlzheng@tencent.com,oleg@redhat.com,akpm@linux-foundation.org From: Andrew Morton Subject: + memcg-mm_update_next_owner-move-for_each_thread-into-try_to_set_owner.patch added to mm-unstable branch Message-Id: <20240626192030.8757EC116B1@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: memcg: mm_update_next_owner: move for_each_thread() into try_to_set_owner() has been added to the -mm mm-unstable branch. Its filename is memcg-mm_update_next_owner-move-for_each_thread-into-try_to_set_owner.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/memcg-mm_update_next_owner-move-for_each_thread-into-try_to_set_owner.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Oleg Nesterov Subject: memcg: mm_update_next_owner: move for_each_thread() into try_to_set_owner() Date: Wed, 26 Jun 2024 17:29:30 +0200 mm_update_next_owner() checks the children / real_parent->children to avoid the "everything else" loop in the likely case, but this won't work if a child/sibling has a zombie leader with ->mm == NULL. Move the for_each_thread() logic into try_to_set_owner(), if nothing else this makes the children/siblings/everything searches more consistent. Link: https://lkml.kernel.org/r/20240626152930.GA17936@redhat.com Signed-off-by: Oleg Nesterov Cc: Christian Brauner Cc: Eric W. Biederman Cc: Jens Axboe Cc: Jinliang Zheng Cc: Mateusz Guzik Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Tycho Andersen Signed-off-by: Andrew Morton --- kernel/exit.c | 40 ++++++++++++++++++++++++---------------- 1 file changed, 24 insertions(+), 16 deletions(-) --- a/kernel/exit.c~memcg-mm_update_next_owner-move-for_each_thread-into-try_to_set_owner +++ a/kernel/exit.c @@ -440,7 +440,7 @@ static void coredump_task_exit(struct ta #ifdef CONFIG_MEMCG /* drops tasklist_lock if succeeds */ -static bool try_to_set_owner(struct task_struct *tsk, struct mm_struct *mm) +static bool __try_to_set_owner(struct task_struct *tsk, struct mm_struct *mm) { bool ret = false; @@ -456,12 +456,28 @@ static bool try_to_set_owner(struct task return ret; } +static bool try_to_set_owner(struct task_struct *g, struct mm_struct *mm) +{ + struct task_struct *t; + + for_each_thread(g, t) { + struct mm_struct *t_mm = READ_ONCE(t->mm); + if (t_mm == mm) { + if (__try_to_set_owner(t, mm)) + return true; + } else if (t_mm) + break; + } + + return false; +} + /* * A task is exiting. If it owned this mm, find a new owner for the mm. */ void mm_update_next_owner(struct mm_struct *mm) { - struct task_struct *c, *g, *p = current; + struct task_struct *g, *p = current; /* * If the exiting or execing task is not the owner, it's @@ -483,19 +499,17 @@ void mm_update_next_owner(struct mm_stru /* * Search in the children */ - list_for_each_entry(c, &p->children, sibling) { - if (c->mm == mm && try_to_set_owner(c, mm)) + list_for_each_entry(g, &p->children, sibling) { + if (try_to_set_owner(g, mm)) goto ret; } - /* * Search in the siblings */ - list_for_each_entry(c, &p->real_parent->children, sibling) { - if (c->mm == mm && try_to_set_owner(c, mm)) + list_for_each_entry(g, &p->real_parent->children, sibling) { + if (try_to_set_owner(g, mm)) goto ret; } - /* * Search through everything else, we should not get here often. */ @@ -504,14 +518,8 @@ void mm_update_next_owner(struct mm_stru break; if (g->flags & PF_KTHREAD) continue; - for_each_thread(g, c) { - struct mm_struct *c_mm = READ_ONCE(c->mm); - if (c_mm == mm) { - if (try_to_set_owner(c, mm)) - goto ret; - } else if (c_mm) - break; - } + if (try_to_set_owner(g, mm)) + goto ret; } read_unlock(&tasklist_lock); /* _ Patches currently in -mm which might be from oleg@redhat.com are memcg-mm_update_next_owner-kill-the-retry-logic.patch memcg-mm_update_next_owner-move-for_each_thread-into-try_to_set_owner.patch zap_pid_ns_processes-dont-send-sigkill-to-sub-threads.patch coredump-simplify-zap_process.patch