From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vk0-f43.google.com (mail-vk0-f43.google.com [209.85.213.43]) by kanga.kvack.org (Postfix) with ESMTP id 80B136B0038 for ; Tue, 17 Nov 2015 10:37:51 -0500 (EST) Received: by vkas68 with SMTP id s68so7877974vka.2 for ; Tue, 17 Nov 2015 07:37:51 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id q189si3241275vkq.12.2015.11.17.07.37.50 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 17 Nov 2015 07:37:50 -0800 (PST) Date: Tue, 17 Nov 2015 17:33:46 +0100 From: Oleg Nesterov Subject: Re: [PATCH] mm: fix incorrect behavior when process virtual address space limit is exceeded Message-ID: <20151117163346.GA12430@redhat.com> References: <1447695379-14526-1-git-send-email-kwapulinski.piotr@gmail.com> <20151117161928.GA9611@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151117161928.GA9611@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Piotr Kwapulinski 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 On 11/17, Oleg Nesterov wrote: > > 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. Or we can simply move this may_expand_vm() block to the caller, do_mmap(). > 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. Yes, but what I actually tried to say is that it would be nice to unexport mmap_region(), arch/tile is the only caller outside of mmap.c. Oleg. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org