From 897ab3e0c49e24b62e2d54d165c7afec6bbca65b Mon Sep 17 00:00:00 2001 From: Mike Rapoport Date: Fri, 24 Feb 2017 14:58:22 -0800 Subject: userfaultfd: non-cooperative: add event for memory unmaps When a non-cooperative userfaultfd monitor copies pages in the background, it may encounter regions that were already unmapped. Addition of UFFD_EVENT_UNMAP allows the uffd monitor to track precisely changes in the virtual memory layout. Since there might be different uffd contexts for the affected VMAs, we first should create a temporary representation for the unmap event for each uffd context and then notify them one by one to the appropriate userfault file descriptors. The event notification occurs after the mmap_sem has been released. [arnd@arndb.de: fix nommu build] Link: http://lkml.kernel.org/r/20170203165141.3665284-1-arnd@arndb.de [mhocko@suse.com: fix nommu build] Link: http://lkml.kernel.org/r/20170202091503.GA22823@dhcp22.suse.cz Link: http://lkml.kernel.org/r/1485542673-24387-3-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport Signed-off-by: Michal Hocko Signed-off-by: Arnd Bergmann Acked-by: Hillf Danton Cc: Andrea Arcangeli Cc: "Dr. David Alan Gilbert" Cc: Mike Kravetz Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/util.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'mm/util.c') diff --git a/mm/util.c b/mm/util.c index 3cb2164f4099..b8f538863b5a 100644 --- a/mm/util.c +++ b/mm/util.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include @@ -297,14 +298,16 @@ unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr, unsigned long ret; struct mm_struct *mm = current->mm; unsigned long populate; + LIST_HEAD(uf); ret = security_mmap_file(file, prot, flag); if (!ret) { if (down_write_killable(&mm->mmap_sem)) return -EINTR; ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff, - &populate); + &populate, &uf); up_write(&mm->mmap_sem); + userfaultfd_unmap_complete(mm, &uf); if (populate) mm_populate(ret, populate); } -- cgit v1.2.3