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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 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-Originating-IP: [10.173.135.154] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To canpemm500002.china.huawei.com (7.192.104.244) X-Rspam-User: X-Stat-Signature: theyieun6zmjtbs5xn3srrdiq4j7i14c X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: C301F1C000D X-HE-Tag: 1715223303-158682 X-HE-Meta: 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 8pwl/yzf IHlnIX1CaXJ9fDeBLP7IIPCNteX/9EyOu7IVIwYtE8xdK9GVhFKONyEvP/ODVN8033+CmNTOGx/odZYuudNABKGaL0svK/3zVqaRmpQxXj1Dg/0B3QnCLlu9N+DiaXbhfJH77DoFPuovFcCf39RKH50jBSdWCvZOr9n4sQRn50wPlS/1+RP1OB7CA542bdfzRcEj3xC255kvdoZk39L8/7aJcQxDITK7qGWa6 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: List-Subscribe: List-Unsubscribe: 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); > } > > /* >