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Message-ID: <55A5BF0F.7090808@gmail.com>
Date: Tue, 14 Jul 2015 22:01:51 -0400
From: David Ahern <dsahern@...il.com>
To: Oleg Nesterov <oleg@...hat.com>, Andrey Vagin <avagin@...nvz.org>
CC: linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Cyrill Gorcunov <gorcunov@...nvz.org>,
Pavel Emelyanov <xemul@...allels.com>,
Roger Luethi <rl@...lgate.ch>, Arnd Bergmann <arnd@...db.de>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Andy Lutomirski <luto@...capital.net>,
Pavel Odintsov <pavel.odintsov@...il.com>
Subject: Re: [PATCH 20/24] task_diag: Only add VMAs for thread_group leader
On 7/14/15 1:47 PM, Oleg Nesterov wrote:
> On 07/06, Andrey Vagin wrote:
>>
>> From: David Ahern <dsahern@...il.com>
>>
>> threads of a process share the same VMAs, so when dumping all threads
>> for all processes only push vma data for group leader.
>
> ...
>
>> @@ -492,6 +493,13 @@ static int task_diag_fill(struct task_struct *tsk, struct sk_buff *skb,
>> }
>>
>> if (show_flags & TASK_DIAG_SHOW_VMA) {
>> + /* if the request is to dump all threads of all processes
>> + * only show VMAs for group leader.
>> + */
>> + if (req->dump_strategy == TASK_DIAG_DUMP_ALL_THREAD &&
>> + !thread_group_leader(tsk))
>> + goto done;
>> +
>
> This doesn't look right, group leader can be a zombie with ->mm == NULL,
Seriously? I'll find some way to track whether VMAs have been dumped for
a pid.
>
>> if (i >= n)
>> err = fill_vma(tsk, skb, cb, &progress, show_flags);
>
> so this probably needs something like find_lock_task_mm().
ok.
Thanks for the review,
David
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