From: Vlastimil Babka <vbabka@suse.cz>
To: "Kirill A. Shutemov" <kirill@shutemov.name>,
Yang Shi <yang.shi@linux.alibaba.com>
Cc: mhocko@kernel.org, willy@infradead.org,
ldufour@linux.vnet.ibm.com, akpm@linux-foundation.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [v2 PATCH 2/2 -mm] mm: brk: dwongrade mmap_sem to read when shrinking
Date: Thu, 27 Sep 2018 15:21:09 +0200 [thread overview]
Message-ID: <3ba966a4-abf9-1363-3e82-41fe73bc0919@suse.cz> (raw)
In-Reply-To: <20180927125025.xnvoh2btdq5kjmai@kshutemo-mobl1>
On 9/27/18 2:50 PM, Kirill A. Shutemov wrote:
>> diff --git a/mm/mmap.c b/mm/mmap.c
>> index 017bcfa..0d2fae1 100644
>> --- a/mm/mmap.c
>> +++ b/mm/mmap.c
>> @@ -193,9 +193,11 @@ static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long
>> unsigned long retval;
>> unsigned long newbrk, oldbrk;
>> struct mm_struct *mm = current->mm;
>> + unsigned long origbrk = mm->brk;
>
> Is it safe to read mm->brk outside the lock?
Good catch! I guess not, parallel brk()'s could then race.
next prev parent reply other threads:[~2018-09-27 13:21 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-26 18:10 [v2 PATCH 1/2 -mm] mm: mremap: dwongrade mmap_sem to read when shrinking Yang Shi
2018-09-26 18:10 ` [v2 PATCH 2/2 -mm] mm: brk: " Yang Shi
2018-09-27 12:14 ` Vlastimil Babka
2018-09-27 16:05 ` Yang Shi
2018-09-27 12:50 ` Kirill A. Shutemov
2018-09-27 13:21 ` Vlastimil Babka [this message]
2018-09-27 16:06 ` Yang Shi
2018-09-27 11:50 ` [v2 PATCH 1/2 -mm] mm: mremap: " Vlastimil Babka
2018-09-27 16:04 ` Yang Shi
2018-09-27 12:46 ` Kirill A. Shutemov
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