From: Mike Rapoport Date: Wed, 2 Aug 2017 20:31:55 +0000 (-0700) Subject: userfaultfd: non-cooperative: notify about unmap of destination during mremap X-Git-Tag: v4.14-rc1~348^2~11 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=b22823719302e88d0e2a6bb06433bd97b175a8d8;p=platform%2Fkernel%2Flinux-rpi.git userfaultfd: non-cooperative: notify about unmap of destination during mremap When mremap is called with MREMAP_FIXED it unmaps memory at the destination address without notifying userfaultfd monitor. If the destination were registered with userfaultfd, the monitor has no way to distinguish between the old and new ranges and to properly relate the page faults that would occur in the destination region. Fixes: 897ab3e0c49e ("userfaultfd: non-cooperative: add event for memory unmaps") Link: http://lkml.kernel.org/r/1500276876-3350-1-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport Acked-by: Pavel Emelyanov Cc: Andrea Arcangeli Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/mremap.c b/mm/mremap.c index 6e3d857..3f23715 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -429,6 +429,7 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr, static unsigned long mremap_to(unsigned long addr, unsigned long old_len, unsigned long new_addr, unsigned long new_len, bool *locked, struct vm_userfaultfd_ctx *uf, + struct list_head *uf_unmap_early, struct list_head *uf_unmap) { struct mm_struct *mm = current->mm; @@ -447,7 +448,7 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, if (addr + old_len > new_addr && new_addr + new_len > addr) goto out; - ret = do_munmap(mm, new_addr, new_len, NULL); + ret = do_munmap(mm, new_addr, new_len, uf_unmap_early); if (ret) goto out; @@ -515,6 +516,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, unsigned long charged = 0; bool locked = false; struct vm_userfaultfd_ctx uf = NULL_VM_UFFD_CTX; + LIST_HEAD(uf_unmap_early); LIST_HEAD(uf_unmap); if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) @@ -542,7 +544,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, if (flags & MREMAP_FIXED) { ret = mremap_to(addr, old_len, new_addr, new_len, - &locked, &uf, &uf_unmap); + &locked, &uf, &uf_unmap_early, &uf_unmap); goto out; } @@ -622,6 +624,7 @@ out: up_write(¤t->mm->mmap_sem); if (locked && new_len > old_len) mm_populate(new_addr + old_len, new_len - old_len); + userfaultfd_unmap_complete(mm, &uf_unmap_early); mremap_userfaultfd_complete(&uf, addr, new_addr, old_len); userfaultfd_unmap_complete(mm, &uf_unmap); return ret;