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authorMike Rapoport <rppt@linux.vnet.ibm.com>2017-02-25 01:58:22 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-25 04:46:55 +0300
commit897ab3e0c49e24b62e2d54d165c7afec6bbca65b (patch)
tree5fa7e09864d6c959cef33849f6cb10ed04e459e4 /mm/mremap.c
parent846b1a0f1db065a8479159dd8fecddb1ebf30547 (diff)
downloadlinux-897ab3e0c49e24b62e2d54d165c7afec6bbca65b.tar.xz
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>
Diffstat (limited to 'mm/mremap.c')
-rw-r--r--mm/mremap.c23
1 files changed, 14 insertions, 9 deletions
diff --git a/mm/mremap.c b/mm/mremap.c
index 8779928d6a70..8233b0105c82 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -252,7 +252,8 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
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 @@ static unsigned long move_vma(struct vm_area_struct *vma,
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 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 vm_userfaultfd_ctx *uf,
+ struct list_head *uf_unmap)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
@@ -435,12 +437,12 @@ 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);
+ 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 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
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 @@ 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);
if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
return ret;
@@ -528,7 +532,7 @@ 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);
+ &locked, &uf, &uf_unmap);
goto out;
}
@@ -538,7 +542,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
* 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 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
}
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 @@ out:
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;
}