From: Oleg Nesterov <oleg@redhat.com>
To: Piotr Kwapulinski <kwapulinski.piotr@gmail.com>
Cc: akpm@linux-foundation.org, cmetcalf@ezchip.com, mszeredi@suse.cz,
viro@zeniv.linux.org.uk, dave@stgolabs.net,
kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com,
aarcange@redhat.com, mhocko@suse.com, iamjoonsoo.kim@lge.com,
jack@suse.cz, xiexiuqi@huawei.com, vbabka@suse.cz,
Vineet.Gupta1@synopsys.com, riel@redhat.com,
gang.chen.5i5j@gmail.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH] mm: fix incorrect behavior when process virtual address space limit is exceeded
Date: Tue, 17 Nov 2015 17:19:28 +0100 [thread overview]
Message-ID: <20151117161928.GA9611@redhat.com> (raw)
In-Reply-To: <1447695379-14526-1-git-send-email-kwapulinski.piotr@gmail.com>
On 11/16, Piotr Kwapulinski wrote:
>
> @@ -1551,7 +1552,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
> * MAP_FIXED may remove pages of mappings that intersects with
> * requested mapping. Account for the pages it would unmap.
> */
> - if (!(vm_flags & MAP_FIXED))
> + if (!(flags & MAP_FIXED))
> return -ENOMEM;
Agree, "vm_flags & MAP_FIXED" makes no sense and just wrong...
Can't we simply remove this check? Afaics it only helps to avoid
count_vma_pages_range() in the unlikely case when may_expand_vm() fails.
And without MAP_FIXED count_vma_pages_range() should be cheap,
find_vma_intersection() should fail.
And afaics arch/tile/mm/elf.c can use do_mmap(MAP_FIXED ...) rather than
mmap_region(), it can be changed by a separate patch. In this case we can
unexport mmap_region().
OTOH, I won't insist, this patch looks fine to me.
Oleg.
next prev parent reply other threads:[~2015-11-17 15:23 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-16 17:36 [PATCH] mm: fix incorrect behavior when process virtual address space limit is exceeded Piotr Kwapulinski
2015-11-16 20:52 ` Michal Hocko
2015-11-17 0:33 ` Michal Hocko
2015-11-18 14:32 ` Cyril Hrubis
2015-11-17 16:19 ` Oleg Nesterov [this message]
2015-11-17 16:33 ` Oleg Nesterov
2015-11-17 17:26 ` [PATCH] mm/mmap.c: remove incorrect MAP_FIXED flag comparison from mmap_region Piotr Kwapulinski
2015-11-18 0:52 ` Andrew Morton
2015-11-18 16:29 ` Piotr Kwapulinski
2015-11-20 16:38 ` [PATCH v2 1/2] mm: fix incorrect behavior when process virtual address space limit is exceeded Piotr Kwapulinski
2015-11-20 16:42 ` [PATCH v2 2/2] mm/mmap.c: remove incorrect MAP_FIXED flag comparison from mmap_region Piotr Kwapulinski
2015-11-23 8:19 ` Michal Hocko
2015-11-23 17:36 ` [PATCH v3] " Piotr Kwapulinski
2015-11-23 22:14 ` Andrew Morton
2015-11-24 16:12 ` Piotr Kwapulinski
2015-11-27 5:27 ` Naoya Horiguchi
2015-11-17 17:38 ` [PATCH] mm: fix incorrect behavior when process virtual address space limit is exceeded Chris Metcalf
2015-11-17 19:03 ` Oleg Nesterov
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