The patch titled
Subject: userfaultfd: shmem: add userfaultfd hook for shared memory faults
has been added to the -mm tree. Its filename is
userfaultfd-shmem-add-userfaultfd-hook-for-shared-memory-faults.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-shmem-add-userfaultfd-hook-for-shared-memory-faults.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-shmem-add-userfaultfd-hook-for-shared-memory-faults.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Subject: userfaultfd: shmem: add userfaultfd hook for shared memory faults
When processing a page fault in shared memory area for not present page,
check the VMA determine if faults are to be handled by userfaultfd. If
so, delegate the page fault to handle_userfault.
Link: http://lkml.kernel.org/r/20161216144821.5183-33-aarcange@xxxxxxxxxx
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Cc: Michael Rapoport <RAPOPORT@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 22 +++++++++++++++-------
1 file changed, 15 insertions(+), 7 deletions(-)
diff -puN mm/shmem.c~userfaultfd-shmem-add-userfaultfd-hook-for-shared-memory-faults mm/shmem.c
--- a/mm/shmem.c~userfaultfd-shmem-add-userfaultfd-hook-for-shared-memory-faults
+++ a/mm/shmem.c
@@ -72,6 +72,7 @@ static struct vfsmount *shm_mnt;
#include <linux/syscalls.h>
#include <linux/fcntl.h>
#include <uapi/linux/memfd.h>
+#include <linux/userfaultfd_k.h>
#include <linux/rmap.h>
#include <linux/uaccess.h>
@@ -118,13 +119,14 @@ static int shmem_replace_page(struct pag
struct shmem_inode_info *info, pgoff_t index);
static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
struct page **pagep, enum sgp_type sgp,
- gfp_t gfp, struct mm_struct *fault_mm, int *fault_type);
+ gfp_t gfp, struct vm_area_struct *vma,
+ struct vm_fault *vmf, int *fault_type);
int shmem_getpage(struct inode *inode, pgoff_t index,
struct page **pagep, enum sgp_type sgp)
{
return shmem_getpage_gfp(inode, index, pagep, sgp,
- mapping_gfp_mask(inode->i_mapping), NULL, NULL);
+ mapping_gfp_mask(inode->i_mapping), NULL, NULL, NULL);
}
static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
@@ -1571,7 +1573,7 @@ static int shmem_replace_page(struct pag
*/
static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
struct page **pagep, enum sgp_type sgp, gfp_t gfp,
- struct mm_struct *fault_mm, int *fault_type)
+ struct vm_area_struct *vma, struct vm_fault *vmf, int *fault_type)
{
struct address_space *mapping = inode->i_mapping;
struct shmem_inode_info *info = SHMEM_I(inode);
@@ -1625,7 +1627,7 @@ repeat:
* bring it back from swap or allocate.
*/
sbinfo = SHMEM_SB(inode->i_sb);
- charge_mm = fault_mm ? : current->mm;
+ charge_mm = vma ? vma->vm_mm : current->mm;
if (swap.val) {
/* Look it up and read it in.. */
@@ -1635,7 +1637,8 @@ repeat:
if (fault_type) {
*fault_type |= VM_FAULT_MAJOR;
count_vm_event(PGMAJFAULT);
- mem_cgroup_count_vm_event(fault_mm, PGMAJFAULT);
+ mem_cgroup_count_vm_event(charge_mm,
+ PGMAJFAULT);
}
/* Here we actually start the io */
page = shmem_swapin(swap, gfp, info, index);
@@ -1704,6 +1707,11 @@ repeat:
swap_free(swap);
} else {
+ if (vma && userfaultfd_missing(vma)) {
+ *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
+ return 0;
+ }
+
/* shmem_symlink() */
if (mapping->a_ops != &shmem_aops)
goto alloc_nohuge;
@@ -1966,7 +1974,7 @@ static int shmem_fault(struct vm_area_st
sgp = SGP_NOHUGE;
error = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, sgp,
- gfp, vma->vm_mm, &ret);
+ gfp, vma, vmf, &ret);
if (error)
return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
return ret;
@@ -4247,7 +4255,7 @@ struct page *shmem_read_mapping_page_gfp
BUG_ON(mapping->a_ops != &shmem_aops);
error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
- gfp, NULL, NULL);
+ gfp, NULL, NULL, NULL);
if (error)
page = ERR_PTR(error);
else
_
Patches currently in -mm which might be from rppt@xxxxxxxxxxxxxxxxxx are
userfaultfd-non-cooperative-dup_userfaultfd-use-mm_count-instead-of-mm_users.patch
userfaultfd-introduce-vma_can_userfault.patch
userfaultfd-shmem-add-shmem_mcopy_atomic_pte-for-userfaultfd-support.patch
userfaultfd-shmem-introduce-vma_is_shmem.patch
userfaultfd-shmem-use-shmem_mcopy_atomic_pte-for-shared-memory.patch
userfaultfd-shmem-add-userfaultfd-hook-for-shared-memory-faults.patch
userfaultfd-shmem-allow-registration-of-shared-memory-ranges.patch
userfaultfd-shmem-add-userfaultfd_shmem-test.patch
userfaultfd-non-cooperative-selftest-introduce-userfaultfd_open.patch
userfaultfd-non-cooperative-selftest-add-ufd-parameter-to-copy_page.patch
userfaultfd-non-cooperative-selftest-add-test-for-fork-madvdontneed-and-remap-events.patch
--
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