On Mon, 24 Aug 2015 13:32:13 +0200 Michal Hocko <mhocko@xxxxxxxxxx> wrote: > On Mon 24-08-15 00:59:39, gang.chen.5i5j@xxxxxx wrote: > > From: Chen Gang <gang.chen.5i5j@xxxxxxxxx> > > > > When failure occurs and return, vma->vm_pgoff is already set, which is > > not a good idea. > > Why? The vma is not inserted anywhere and the failure path is supposed > to simply free the vma. Yes, it's pretty marginal but I suppose the code is a bit better with the patch than without. I did this: From: Chen Gang <gang.chen.5i5j@xxxxxxxxx> Subject: mm/mmap.c:insert_vm_struct(): check for failure before setting values There's no point in initializing vma->vm_pgoff if the insertion attempt will be failing anyway. Run the checks before performing the initialization. Signed-off-by: Chen Gang <gang.chen.5i5j@xxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/mmap.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff -puN mm/mmap.c~mm-mmap-check-all-failures-before-set-values mm/mmap.c --- a/mm/mmap.c~mm-mmap-check-all-failures-before-set-values +++ a/mm/mmap.c @@ -2859,6 +2859,13 @@ int insert_vm_struct(struct mm_struct *m struct vm_area_struct *prev; struct rb_node **rb_link, *rb_parent; + if (find_vma_links(mm, vma->vm_start, vma->vm_end, + &prev, &rb_link, &rb_parent)) + return -ENOMEM; + if ((vma->vm_flags & VM_ACCOUNT) && + security_vm_enough_memory_mm(mm, vma_pages(vma))) + return -ENOMEM; + /* * The vm_pgoff of a purely anonymous vma should be irrelevant * until its first write fault, when page's anon_vma and index @@ -2875,12 +2882,6 @@ int insert_vm_struct(struct mm_struct *m BUG_ON(vma->anon_vma); vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; } - if (find_vma_links(mm, vma->vm_start, vma->vm_end, - &prev, &rb_link, &rb_parent)) - return -ENOMEM; - if ((vma->vm_flags & VM_ACCOUNT) && - security_vm_enough_memory_mm(mm, vma_pages(vma))) - return -ENOMEM; vma_link(mm, vma, prev, rb_link, rb_parent); return 0; _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>