From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162952AbbKTQjx (ORCPT ); Fri, 20 Nov 2015 11:39:53 -0500 Received: from mail-lf0-f65.google.com ([209.85.215.65]:34862 "EHLO mail-lf0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1162616AbbKTQjt (ORCPT ); Fri, 20 Nov 2015 11:39:49 -0500 From: Piotr Kwapulinski To: akpm@linux-foundation.org Cc: mhocko@suse.com, oleg@redhat.com, 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, 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, Piotr Kwapulinski Subject: [PATCH v2 1/2] mm: fix incorrect behavior when process virtual address space limit is exceeded Date: Fri, 20 Nov 2015 17:38:53 +0100 Message-Id: <1448037533-4662-1-git-send-email-kwapulinski.piotr@gmail.com> X-Mailer: git-send-email 2.6.2 In-Reply-To: <20151118162939.GA1842@home.local> References: <20151118162939.GA1842@home.local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following flag comparison in mmap_region makes no sense: if (!(vm_flags & MAP_FIXED)) return -ENOMEM; The condition is false even if MAP_FIXED is not set what causes the unnecessary find_vma call. MAP_FIXED has the same value as VM_MAYREAD. The vm_flags must not be compared with MAP_FIXED. The vm_flags may only be compared with VM_* flags. The mmap executes slightly longer when MAP_FIXED is not set and RLIMIT_AS is exceeded. Fix the issue by introducing a new parameter to mmap_region which forwards the mmap flags and now the MAP_FIXED can be checked properly. Tile and its arch_setup_additional_pages as the user of mmap_region has to be specific about its mmap flags now. Signed-off-by: Piotr Kwapulinski --- arch/tile/mm/elf.c | 1 + include/linux/mm.h | 3 ++- mm/mmap.c | 7 ++++--- 3 files changed, 7 insertions(+), 4 deletions(-) diff --git a/arch/tile/mm/elf.c b/arch/tile/mm/elf.c index 6225cc9..dae4b33 100644 --- a/arch/tile/mm/elf.c +++ b/arch/tile/mm/elf.c @@ -142,6 +142,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, if (!retval) { unsigned long addr = MEM_USER_INTRPT; addr = mmap_region(NULL, addr, INTRPT_SIZE, + MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE, VM_READ|VM_EXEC| VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 0); if (addr > (unsigned long) -PAGE_SIZE) diff --git a/include/linux/mm.h b/include/linux/mm.h index 00bad77..f1a203f 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1911,7 +1911,8 @@ extern int install_special_mapping(struct mm_struct *mm, extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); extern unsigned long mmap_region(struct file *file, unsigned long addr, - unsigned long len, vm_flags_t vm_flags, unsigned long pgoff); + unsigned long len, unsigned long mmap_flags, + vm_flags_t vm_flags, unsigned long pgoff); extern unsigned long do_mmap(struct file *file, unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate); diff --git a/mm/mmap.c b/mm/mmap.c index 2ce04a6..8f3427f 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1399,7 +1399,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr, vm_flags |= VM_NORESERVE; } - addr = mmap_region(file, addr, len, vm_flags, pgoff); + addr = mmap_region(file, addr, len, flags, vm_flags, pgoff); if (!IS_ERR_VALUE(addr) && ((vm_flags & VM_LOCKED) || (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) @@ -1535,7 +1535,8 @@ static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags) } unsigned long mmap_region(struct file *file, unsigned long addr, - unsigned long len, vm_flags_t vm_flags, unsigned long pgoff) + unsigned long len, unsigned long mmap_flags, + vm_flags_t vm_flags, unsigned long pgoff) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma, *prev; @@ -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 (!(mmap_flags & MAP_FIXED)) return -ENOMEM; nr_pages = count_vma_pages_range(mm, addr, addr + len); -- 2.6.2