From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) (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 D4F7B13BC35 for ; Thu, 9 May 2024 02:55:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.187 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715223304; cv=none; b=GAyVQqRFd31zzhaJTPIgoetvwSNtEvhBs8GsJFy1N8koI1DB3Q9/TiBoPSfJRBV4Sn/La5JYRSkwzDrnzbWVkAwO35jGmbEuVKvOSMnm9ZJ4HWOlgKp/uH+4GBTOj/hLBGMOcL/KWIIUdLCXRhiOGsuLkHW82JjGk+E3K0jgLrc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715223304; c=relaxed/simple; bh=auRLcGEMSLstBD+6gugZx6gvyMdXRAmUdtAvgnFwsIQ=; h=Subject:To:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=c8auafeq770VIUAt0jiG0gNCfif8hKtF8dzptqOYblnoiETQXaYLUrPUOz+2uffss4m6fEfEeI7U0/d38sUO+PuS9BrzVQJ1Z7+qHKya8QdKHAd0+lbl7jpG0vGT1T/sd6F0rCw+uZcAVaySkv7rH0CJImhiT2TXOiuisDg90Ro= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.174]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4VZc3Z1nGHzvSW1; Thu, 9 May 2024 10:51:38 +0800 (CST) Received: from canpemm500002.china.huawei.com (unknown [7.192.104.244]) by mail.maildlp.com (Postfix) with ESMTPS id 1AABC140414; Thu, 9 May 2024 10:54:59 +0800 (CST) Received: from [10.173.135.154] (10.173.135.154) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.35; Thu, 9 May 2024 10:54:58 +0800 Subject: Re: [PATCH 1/3] mm/memory-failure: try to send SIGBUS even if unmap failed To: Jane Chu , , , , References: <20240501232458.3919593-1-jane.chu@oracle.com> <20240501232458.3919593-2-jane.chu@oracle.com> From: Miaohe Lin Message-ID: Date: Thu, 9 May 2024 10:54:58 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20240501232458.3919593-2-jane.chu@oracle.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To canpemm500002.china.huawei.com (7.192.104.244) On 2024/5/2 7:24, Jane Chu wrote: > For years when it comes down to kill a process due to hwpoison, > a SIGBUS is delivered only if unmap has been successful. > Otherwise, a SIGKILL is delivered. And the reason for that is > to prevent the involved process from accessing the hwpoisoned > page again. > > Since then a lot has changed, a hwpoisoned page is marked and > upon being re-accessed, the process will be killed immediately. > So let's take out the '!unmap_success' factor and try to deliver > SIGBUS if possible. > > Signed-off-by: Jane Chu > --- > mm/memory-failure.c | 13 ++++--------- > 1 file changed, 4 insertions(+), 9 deletions(-) > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index 9e62a00b46dd..7fcf182abb96 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -519,19 +519,14 @@ void add_to_kill_ksm(struct task_struct *tsk, struct page *p, > * Also when FAIL is set do a force kill because something went > * wrong earlier. > */ > -static void kill_procs(struct list_head *to_kill, int forcekill, bool fail, > +static void kill_procs(struct list_head *to_kill, int forcekill, > unsigned long pfn, int flags) > { > struct to_kill *tk, *next; > > list_for_each_entry_safe(tk, next, to_kill, nd) { > if (forcekill) { > - /* > - * In case something went wrong with munmapping > - * make sure the process doesn't catch the > - * signal and then access the memory. Just kill it. > - */ > - if (fail || tk->addr == -EFAULT) { > + if (tk->addr == -EFAULT) { > pr_err("%#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n", > pfn, tk->tsk->comm, tk->tsk->pid); > do_send_sig_info(SIGKILL, SEND_SIG_PRIV, > @@ -1666,7 +1661,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn, > */ There is comment above the forcekill saying: When there was a problem unmapping earlier use a more force-full uncatchable kill to prevent any accesses to the poisoned memory. This might need to be changed too. Thanks. . > forcekill = PageDirty(hpage) || (flags & MF_MUST_KILL) || > !unmap_success; > - kill_procs(&tokill, forcekill, !unmap_success, pfn, flags); > + kill_procs(&tokill, forcekill, pfn, flags); > > return unmap_success; > } > @@ -1730,7 +1725,7 @@ static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn, > unmap_mapping_range(mapping, start, size, 0); > } > > - kill_procs(to_kill, flags & MF_MUST_KILL, false, pfn, flags); > + kill_procs(to_kill, flags & MF_MUST_KILL, pfn, flags); > } > > /* >