This is a note to let you know that I've just added the patch titled mm: fix regression in remap_file_pages() emulation to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mm-fix-regression-in-remap_file_pages-emulation.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 48f7df329474b49d83d0dffec1b6186647f11976 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Date: Wed, 17 Feb 2016 13:11:15 -0800 Subject: mm: fix regression in remap_file_pages() emulation From: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> commit 48f7df329474b49d83d0dffec1b6186647f11976 upstream. Grazvydas Ignotas has reported a regression in remap_file_pages() emulation. Testcase: #define _GNU_SOURCE #include <assert.h> #include <stdlib.h> #include <stdio.h> #include <sys/mman.h> #define SIZE (4096 * 3) int main(int argc, char **argv) { unsigned long *p; long i; p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); if (p == MAP_FAILED) { perror("mmap"); return -1; } for (i = 0; i < SIZE / 4096; i++) p[i * 4096 / sizeof(*p)] = i; if (remap_file_pages(p, 4096, 0, 1, 0)) { perror("remap_file_pages"); return -1; } if (remap_file_pages(p, 4096 * 2, 0, 1, 0)) { perror("remap_file_pages"); return -1; } assert(p[0] == 1); munmap(p, SIZE); return 0; } The second remap_file_pages() fails with -EINVAL. The reason is that remap_file_pages() emulation assumes that the target vma covers whole area we want to over map. That assumption is broken by first remap_file_pages() call: it split the area into two vma. The solution is to check next adjacent vmas, if they map the same file with the same flags. Fixes: c8d78c1823f4 ("mm: replace remap_file_pages() syscall with emulation") Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reported-by: Grazvydas Ignotas <notasas@xxxxxxxxx> Tested-by: Grazvydas Ignotas <notasas@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/mmap.c | 34 +++++++++++++++++++++++++++++----- 1 file changed, 29 insertions(+), 5 deletions(-) --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2668,12 +2668,29 @@ SYSCALL_DEFINE5(remap_file_pages, unsign if (!vma || !(vma->vm_flags & VM_SHARED)) goto out; - if (start < vma->vm_start || start + size > vma->vm_end) + if (start < vma->vm_start) goto out; - if (pgoff == linear_page_index(vma, start)) { - ret = 0; - goto out; + if (start + size > vma->vm_end) { + struct vm_area_struct *next; + + for (next = vma->vm_next; next; next = next->vm_next) { + /* hole between vmas ? */ + if (next->vm_start != next->vm_prev->vm_end) + goto out; + + if (next->vm_file != vma->vm_file) + goto out; + + if (next->vm_flags != vma->vm_flags) + goto out; + + if (start + size <= next->vm_end) + break; + } + + if (!next) + goto out; } prot |= vma->vm_flags & VM_READ ? PROT_READ : 0; @@ -2683,9 +2700,16 @@ SYSCALL_DEFINE5(remap_file_pages, unsign flags &= MAP_NONBLOCK; flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE; if (vma->vm_flags & VM_LOCKED) { + struct vm_area_struct *tmp; flags |= MAP_LOCKED; + /* drop PG_Mlocked flag for over-mapped range */ - munlock_vma_pages_range(vma, start, start + size); + for (tmp = vma; tmp->vm_start >= start + size; + tmp = tmp->vm_next) { + munlock_vma_pages_range(tmp, + max(tmp->vm_start, start), + min(tmp->vm_end, start + size)); + } } file = get_file(vma->vm_file); Patches currently in stable-queue which might be from kirill.shutemov@xxxxxxxxxxxxxxx are queue-4.4/mm-thp-khugepaged-call-pte-flush-at-the-time-of-collapse.patch queue-4.4/ipc-shm-handle-removed-segments-gracefully-in-shm_mmap.patch queue-4.4/drivers-scsi-sg.c-mark-vma-as-vm_io-to-prevent-migration.patch queue-4.4/mm-fix-mlock-accouting.patch queue-4.4/mm-replace-vma_lock_anon_vma-with-anon_vma_lock_read-write.patch queue-4.4/mm-fix-regression-in-remap_file_pages-emulation.patch queue-4.4/scsi-add-marvell-console-to-vpd-blacklist.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html