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 <rppt@linux.vnet.ibm.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/mmap.c b/mm/mmap.c
index 13d16a2..1cec28d 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -176,7 +176,7 @@
return next;
}
-static int do_brk(unsigned long addr, unsigned long len);
+static int do_brk(unsigned long addr, unsigned long len, struct list_head *uf);
SYSCALL_DEFINE1(brk, unsigned long, brk)
{
@@ -185,6 +185,7 @@
struct mm_struct *mm = current->mm;
unsigned long min_brk;
bool populate;
+ LIST_HEAD(uf);
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
@@ -222,7 +223,7 @@
/* Always allow shrinking brk. */
if (brk <= mm->brk) {
- if (!do_munmap(mm, newbrk, oldbrk-newbrk))
+ if (!do_munmap(mm, newbrk, oldbrk-newbrk, &uf))
goto set_brk;
goto out;
}
@@ -232,13 +233,14 @@
goto out;
/* Ok, looks good - let it rip. */
- if (do_brk(oldbrk, newbrk-oldbrk) < 0)
+ if (do_brk(oldbrk, newbrk-oldbrk, &uf) < 0)
goto out;
set_brk:
mm->brk = brk;
populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
up_write(&mm->mmap_sem);
+ userfaultfd_unmap_complete(mm, &uf);
if (populate)
mm_populate(oldbrk, newbrk - oldbrk);
return brk;
@@ -1304,7 +1306,8 @@
unsigned long do_mmap(struct file *file, unsigned long addr,
unsigned long len, unsigned long prot,
unsigned long flags, vm_flags_t vm_flags,
- unsigned long pgoff, unsigned long *populate)
+ unsigned long pgoff, unsigned long *populate,
+ struct list_head *uf)
{
struct mm_struct *mm = current->mm;
int pkey = 0;
@@ -1447,7 +1450,7 @@
vm_flags |= VM_NORESERVE;
}
- addr = mmap_region(file, addr, len, vm_flags, pgoff);
+ addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
if (!IS_ERR_VALUE(addr) &&
((vm_flags & VM_LOCKED) ||
(flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
@@ -1583,7 +1586,8 @@
}
unsigned long mmap_region(struct file *file, unsigned long addr,
- unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
+ unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
+ struct list_head *uf)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma, *prev;
@@ -1609,7 +1613,7 @@
/* Clear old maps */
while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
&rb_parent)) {
- if (do_munmap(mm, addr, len))
+ if (do_munmap(mm, addr, len, uf))
return -ENOMEM;
}
@@ -2579,7 +2583,8 @@
* work. This now handles partial unmappings.
* Jeremy Fitzhardinge <jeremy@goop.org>
*/
-int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
+int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
+ struct list_head *uf)
{
unsigned long end;
struct vm_area_struct *vma, *prev, *last;
@@ -2603,6 +2608,13 @@
if (vma->vm_start >= end)
return 0;
+ if (uf) {
+ int error = userfaultfd_unmap_prep(vma, start, end, uf);
+
+ if (error)
+ return error;
+ }
+
/*
* If we need to split any vma, do it now to save pain later.
*
@@ -2668,12 +2680,14 @@
{
int ret;
struct mm_struct *mm = current->mm;
+ LIST_HEAD(uf);
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
- ret = do_munmap(mm, start, len);
+ ret = do_munmap(mm, start, len, &uf);
up_write(&mm->mmap_sem);
+ userfaultfd_unmap_complete(mm, &uf);
return ret;
}
EXPORT_SYMBOL(vm_munmap);
@@ -2773,7 +2787,7 @@
file = get_file(vma->vm_file);
ret = do_mmap_pgoff(vma->vm_file, start, size,
- prot, flags, pgoff, &populate);
+ prot, flags, pgoff, &populate, NULL);
fput(file);
out:
up_write(&mm->mmap_sem);
@@ -2799,7 +2813,7 @@
* anonymous maps. eventually we may be able to do some
* brk-specific accounting here.
*/
-static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
+static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags, struct list_head *uf)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma, *prev;
@@ -2838,7 +2852,7 @@
*/
while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
&rb_parent)) {
- if (do_munmap(mm, addr, len))
+ if (do_munmap(mm, addr, len, uf))
return -ENOMEM;
}
@@ -2885,9 +2899,9 @@
return 0;
}
-static int do_brk(unsigned long addr, unsigned long len)
+static int do_brk(unsigned long addr, unsigned long len, struct list_head *uf)
{
- return do_brk_flags(addr, len, 0);
+ return do_brk_flags(addr, len, 0, uf);
}
int vm_brk_flags(unsigned long addr, unsigned long len, unsigned long flags)
@@ -2895,13 +2909,15 @@
struct mm_struct *mm = current->mm;
int ret;
bool populate;
+ LIST_HEAD(uf);
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
- ret = do_brk_flags(addr, len, flags);
+ ret = do_brk_flags(addr, len, flags, &uf);
populate = ((mm->def_flags & VM_LOCKED) != 0);
up_write(&mm->mmap_sem);
+ userfaultfd_unmap_complete(mm, &uf);
if (populate && !ret)
mm_populate(addr, len);
return ret;
diff --git a/mm/mremap.c b/mm/mremap.c
index 8779928..8233b01 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -252,7 +252,8 @@
static unsigned long move_vma(struct vm_area_struct *vma,
unsigned long old_addr, unsigned long old_len,
unsigned long new_len, unsigned long new_addr,
- bool *locked, struct vm_userfaultfd_ctx *uf)
+ bool *locked, struct vm_userfaultfd_ctx *uf,
+ struct list_head *uf_unmap)
{
struct mm_struct *mm = vma->vm_mm;
struct vm_area_struct *new_vma;
@@ -341,7 +342,7 @@
if (unlikely(vma->vm_flags & VM_PFNMAP))
untrack_pfn_moved(vma);
- if (do_munmap(mm, old_addr, old_len) < 0) {
+ if (do_munmap(mm, old_addr, old_len, uf_unmap) < 0) {
/* OOM: unable to split vma, just get accounts right */
vm_unacct_memory(excess >> PAGE_SHIFT);
excess = 0;
@@ -417,7 +418,8 @@
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 vm_userfaultfd_ctx *uf,
+ struct list_head *uf_unmap)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
@@ -435,12 +437,12 @@
if (addr + old_len > new_addr && new_addr + new_len > addr)
goto out;
- ret = do_munmap(mm, new_addr, new_len);
+ ret = do_munmap(mm, new_addr, new_len, NULL);
if (ret)
goto out;
if (old_len >= new_len) {
- ret = do_munmap(mm, addr+new_len, old_len - new_len);
+ ret = do_munmap(mm, addr+new_len, old_len - new_len, uf_unmap);
if (ret && old_len != new_len)
goto out;
old_len = new_len;
@@ -462,7 +464,8 @@
if (offset_in_page(ret))
goto out1;
- ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, uf);
+ ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, uf,
+ uf_unmap);
if (!(offset_in_page(ret)))
goto out;
out1:
@@ -502,6 +505,7 @@
unsigned long charged = 0;
bool locked = false;
struct vm_userfaultfd_ctx uf = NULL_VM_UFFD_CTX;
+ LIST_HEAD(uf_unmap);
if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
return ret;
@@ -528,7 +532,7 @@
if (flags & MREMAP_FIXED) {
ret = mremap_to(addr, old_len, new_addr, new_len,
- &locked, &uf);
+ &locked, &uf, &uf_unmap);
goto out;
}
@@ -538,7 +542,7 @@
* do_munmap does all the needed commit accounting
*/
if (old_len >= new_len) {
- ret = do_munmap(mm, addr+new_len, old_len - new_len);
+ ret = do_munmap(mm, addr+new_len, old_len - new_len, &uf_unmap);
if (ret && old_len != new_len)
goto out;
ret = addr;
@@ -598,7 +602,7 @@
}
ret = move_vma(vma, addr, old_len, new_len, new_addr,
- &locked, &uf);
+ &locked, &uf, &uf_unmap);
}
out:
if (offset_in_page(ret)) {
@@ -609,5 +613,6 @@
if (locked && new_len > old_len)
mm_populate(new_addr + old_len, new_len - old_len);
mremap_userfaultfd_complete(&uf, addr, new_addr, old_len);
+ userfaultfd_unmap_complete(mm, &uf_unmap);
return ret;
}
diff --git a/mm/nommu.c b/mm/nommu.c
index 215c622..fe9f4fa 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1205,7 +1205,8 @@
unsigned long flags,
vm_flags_t vm_flags,
unsigned long pgoff,
- unsigned long *populate)
+ unsigned long *populate,
+ struct list_head *uf)
{
struct vm_area_struct *vma;
struct vm_region *region;
@@ -1577,7 +1578,7 @@
* - under NOMMU conditions the chunk to be unmapped must be backed by a single
* VMA, though it need not cover the whole VMA
*/
-int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
+int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf)
{
struct vm_area_struct *vma;
unsigned long end;
@@ -1643,7 +1644,7 @@
int ret;
down_write(&mm->mmap_sem);
- ret = do_munmap(mm, addr, len);
+ ret = do_munmap(mm, addr, len, NULL);
up_write(&mm->mmap_sem);
return ret;
}
diff --git a/mm/util.c b/mm/util.c
index 3cb2164..b8f5388 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -11,6 +11,7 @@
#include <linux/mman.h>
#include <linux/hugetlb.h>
#include <linux/vmalloc.h>
+#include <linux/userfaultfd_k.h>
#include <asm/sections.h>
#include <linux/uaccess.h>
@@ -297,14 +298,16 @@
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);
}