From a1fde08c74e90accd62d4cfdbf580d2ede938fe7 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 4 May 2011 21:30:28 -0700 Subject: VM: skip the stack guard page lookup in get_user_pages only for mlock The logic in __get_user_pages() used to skip the stack guard page lookup whenever the caller wasn't interested in seeing what the actual page was. But Michel Lespinasse points out that there are cases where we don't care about the physical page itself (so 'pages' may be NULL), but do want to make sure a page is mapped into the virtual address space. So using the existence of the "pages" array as an indication of whether to look up the guard page or not isn't actually so great, and we really should just use the FOLL_MLOCK bit. But because that bit was only set for the VM_LOCKED case (and not all vma's necessarily have it, even for mlock()), we couldn't do that originally. Fix that by moving the VM_LOCKED check deeper into the call-chain, which actually simplifies many things. Now mlock() gets simpler, and we can also check for FOLL_MLOCK in __get_user_pages() and the code ends up much more straightforward. Reported-and-reviewed-by: Michel Lespinasse Cc: stable@kernel.org Signed-off-by: Linus Torvalds --- mm/mlock.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'mm/mlock.c') diff --git a/mm/mlock.c b/mm/mlock.c index 6b55e3efe0df..516b2c2ddd5a 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -162,7 +162,7 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma, VM_BUG_ON(end > vma->vm_end); VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); - gup_flags = FOLL_TOUCH; + gup_flags = FOLL_TOUCH | FOLL_MLOCK; /* * We want to touch writable mappings with a write fault in order * to break COW, except for shared mappings because these don't COW @@ -178,9 +178,6 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma, if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)) gup_flags |= FOLL_FORCE; - if (vma->vm_flags & VM_LOCKED) - gup_flags |= FOLL_MLOCK; - return __get_user_pages(current, mm, addr, nr_pages, gup_flags, NULL, NULL, nonblocking); } -- cgit v1.2.3 From ca16d140af91febe25daeb9e032bf8bd46b8c31f Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Thu, 26 May 2011 19:16:19 +0900 Subject: mm: don't access vm_flags as 'int' The type of vma->vm_flags is 'unsigned long'. Neither 'int' nor 'unsigned int'. This patch fixes such misuse. Signed-off-by: KOSAKI Motohiro [ Changed to use a typedef - we'll extend it to cover more cases later, since there has been discussion about making it a 64-bit type.. - Linus ] Signed-off-by: Linus Torvalds --- mm/mlock.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'mm/mlock.c') diff --git a/mm/mlock.c b/mm/mlock.c index 516b2c2ddd5a..048260c4e02e 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -307,13 +307,13 @@ void munlock_vma_pages_range(struct vm_area_struct *vma, * For vmas that pass the filters, merge/split as appropriate. */ static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev, - unsigned long start, unsigned long end, unsigned int newflags) + unsigned long start, unsigned long end, vm_flags_t newflags) { struct mm_struct *mm = vma->vm_mm; pgoff_t pgoff; int nr_pages; int ret = 0; - int lock = newflags & VM_LOCKED; + int lock = !!(newflags & VM_LOCKED); if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm)) @@ -385,7 +385,7 @@ static int do_mlock(unsigned long start, size_t len, int on) prev = vma; for (nstart = start ; ; ) { - unsigned int newflags; + vm_flags_t newflags; /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ @@ -524,7 +524,7 @@ static int do_mlockall(int flags) goto out; for (vma = current->mm->mmap; vma ; vma = prev->vm_next) { - unsigned int newflags; + vm_flags_t newflags; newflags = vma->vm_flags | VM_LOCKED; if (!(flags & MCL_CURRENT)) -- cgit v1.2.3