From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Oleg Nesterov , KOSAKI Motohiro , Steven T Hampson , Mel Gorman , Rik van Riel , Andi Kleen , Andrew Morton , Linus Torvalds Subject: [ 90/99] mm: mempolicy: fix mbind_range() && vma_adjust() interaction Date: Fri, 2 Aug 2013 18:08:43 +0800 Message-Id: <20130802100238.484949456@linuxfoundation.org> In-Reply-To: <20130802100225.478715166@linuxfoundation.org> References: <20130802100225.478715166@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Oleg Nesterov commit 3964acd0dbec123aa0a621973a2a0580034b4788 upstream. vma_adjust() does vma_set_policy(vma, vma_policy(next)) and this is doubly wrong: 1. This leaks vma->vm_policy if it is not NULL and not equal to next->vm_policy. This can happen if vma_merge() expands "area", not prev (case 8). 2. This sets the wrong policy if vma_merge() joins prev and area, area is the vma the caller needs to update and it still has the old policy. Revert commit 1444f92c8498 ("mm: merging memory blocks resets mempolicy") which introduced these problems. Change mbind_range() to recheck mpol_equal() after vma_merge() to fix the problem that commit tried to address. Signed-off-by: Oleg Nesterov Acked-by: KOSAKI Motohiro Cc: Steven T Hampson Cc: Mel Gorman Cc: KOSAKI Motohiro Cc: Rik van Riel Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/mempolicy.c | 6 +++++- mm/mmap.c | 2 +- 2 files changed, 6 insertions(+), 2 deletions(-) --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -732,7 +732,10 @@ static int mbind_range(struct mm_struct if (prev) { vma = prev; next = vma->vm_next; - continue; + if (mpol_equal(vma_policy(vma), new_pol)) + continue; + /* vma_merge() joined vma && vma->next, case 8 */ + goto replace; } if (vma->vm_start != vmstart) { err = split_vma(vma->vm_mm, vma, vmstart, 1); @@ -744,6 +747,7 @@ static int mbind_range(struct mm_struct if (err) goto out; } + replace: err = vma_replace_policy(vma, new_pol); if (err) goto out; --- a/mm/mmap.c +++ b/mm/mmap.c @@ -865,7 +865,7 @@ again: remove_next = 1 + (end > next-> if (next->anon_vma) anon_vma_merge(vma, next); mm->map_count--; - vma_set_policy(vma, vma_policy(next)); + mpol_put(vma_policy(next)); kmem_cache_free(vm_area_cachep, next); /* * In mprotect's case 6 (see comments on vma_merge),