From: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Subject: userfaultfd: non-cooperative: add madvise() event for MADV_FREE request MADV_FREE is identical to MADV_DONTNEED from the point of view of uffd monitor. The monitor has to stop handling #PF events in the range being freed. We are reusing userfaultfd_remove callback along with the logic required to re-get and re-validate the VMA which may change or disappear because userfaultfd_remove releases mmap_sem. Link: http://lkml.kernel.org/r/1497876311-18615-1-git-send-email-rppt@xxxxxxxxxxxxxxxxxx Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/madvise.c | 42 ++++++++++++++++++++++-------------------- 1 file changed, 22 insertions(+), 20 deletions(-) diff -puN mm/madvise.c~userfaultfd-non-cooperative-add-madvise-event-for-madv_free-request mm/madvise.c --- a/mm/madvise.c~userfaultfd-non-cooperative-add-madvise-event-for-madv_free-request +++ a/mm/madvise.c @@ -451,9 +451,6 @@ static int madvise_free_single_vma(struc struct mm_struct *mm = vma->vm_mm; struct mmu_gather tlb; - if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP)) - return -EINVAL; - /* MADV_FREE works for only anon vma at the moment */ if (!vma_is_anonymous(vma)) return -EINVAL; @@ -477,14 +474,6 @@ static int madvise_free_single_vma(struc return 0; } -static long madvise_free(struct vm_area_struct *vma, - struct vm_area_struct **prev, - unsigned long start, unsigned long end) -{ - *prev = vma; - return madvise_free_single_vma(vma, start, end); -} - /* * Application no longer needs these pages. If the pages are dirty, * it's OK to just throw them away. The app will be more careful about @@ -504,9 +493,17 @@ static long madvise_free(struct vm_area_ * An interface that causes the system to free clean pages and flush * dirty pages is already available as msync(MS_INVALIDATE). */ -static long madvise_dontneed(struct vm_area_struct *vma, - struct vm_area_struct **prev, - unsigned long start, unsigned long end) +static long madvise_dontneed_single_vma(struct vm_area_struct *vma, + unsigned long start, unsigned long end) +{ + zap_page_range(vma, start, end - start); + return 0; +} + +static long madvise_dontneed_free(struct vm_area_struct *vma, + struct vm_area_struct **prev, + unsigned long start, unsigned long end, + int behavior) { *prev = vma; if (!can_madv_dontneed_vma(vma)) @@ -526,7 +523,8 @@ static long madvise_dontneed(struct vm_a * is also < vma->vm_end. If start < * vma->vm_start it means an hole materialized * in the user address space within the - * virtual range passed to MADV_DONTNEED. + * virtual range passed to MADV_DONTNEED + * or MADV_FREE. */ return -ENOMEM; } @@ -537,7 +535,7 @@ static long madvise_dontneed(struct vm_a * Don't fail if end > vma->vm_end. If the old * vma was splitted while the mmap_sem was * released the effect of the concurrent - * operation may not cause MADV_DONTNEED to + * operation may not cause madvise() to * have an undefined result. There may be an * adjacent next vma that we'll walk * next. userfaultfd_remove() will generate an @@ -549,8 +547,13 @@ static long madvise_dontneed(struct vm_a } VM_WARN_ON(start >= end); } - zap_page_range(vma, start, end - start); - return 0; + + if (behavior == MADV_DONTNEED) + return madvise_dontneed_single_vma(vma, start, end); + else if (behavior == MADV_FREE) + return madvise_free_single_vma(vma, start, end); + else + return -EINVAL; } /* @@ -656,9 +659,8 @@ madvise_vma(struct vm_area_struct *vma, case MADV_WILLNEED: return madvise_willneed(vma, prev, start, end); case MADV_FREE: - return madvise_free(vma, prev, start, end); case MADV_DONTNEED: - return madvise_dontneed(vma, prev, start, end); + return madvise_dontneed_free(vma, prev, start, end, behavior); default: return madvise_behavior(vma, prev, start, end, behavior); } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
