From fdf4c587a793ba87935e38e7f25a9540bc9a7b95 Mon Sep 17 00:00:00 2001 From: Michel Lespinasse Date: Mon, 31 Jan 2011 17:03:41 -0800 Subject: [PATCH] mlock: operate on any regions with protection != PROT_NONE As Tao Ma noticed, change 5ecfda0 breaks blktrace. This is because blktrace mmaps a file with PROT_WRITE permissions but without PROT_READ, so my attempt to not unnecessarity break COW during mlock ended up causing mlock to fail with a permission problem. I am proposing to let mlock ignore vma protection in all cases except PROT_NONE. In particular, mlock should not fail for PROT_WRITE regions (as in the blktrace case, which broke at 5ecfda0) or for PROT_EXEC regions (which seem to me like they were always broken). Signed-off-by: Michel Lespinasse Acked-by: Rik van Riel Signed-off-by: Linus Torvalds --- mm/mlock.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/mlock.c b/mm/mlock.c index 13e81ee8be9d..c3924c7f00be 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -178,6 +178,13 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma, if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE) gup_flags |= FOLL_WRITE; + /* + * We want mlock to succeed for regions that have any permissions + * other than PROT_NONE. + */ + if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)) + gup_flags |= FOLL_FORCE; + if (vma->vm_flags & VM_LOCKED) gup_flags |= FOLL_MLOCK; -- 2.20.1