The patch titled
Subject: mm: factor out functionality to finish page faults
has been added to the -mm tree. Its filename is
mm-factor-out-functionality-to-finish-page-faults.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-factor-out-functionality-to-finish-page-faults.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-factor-out-functionality-to-finish-page-faults.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
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------------------------------------------------------
From: Jan Kara <jack@xxxxxxx>
Subject: mm: factor out functionality to finish page faults
Introduce finish_fault() as a helper function for finishing page faults.
It is rather thin wrapper around alloc_set_pte() but since we'd want to
call this from DAX code or filesystems, it is still useful to avoid some
boilerplate code.
Link: http://lkml.kernel.org/r/1479460644-25076-10-git-send-email-jack@xxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 1
mm/memory.c | 44 ++++++++++++++++++++++++++++++++++---------
2 files changed, 36 insertions(+), 9 deletions(-)
diff -puN include/linux/mm.h~mm-factor-out-functionality-to-finish-page-faults include/linux/mm.h
--- a/include/linux/mm.h~mm-factor-out-functionality-to-finish-page-faults
+++ a/include/linux/mm.h
@@ -620,6 +620,7 @@ static inline pte_t maybe_mkwrite(pte_t
int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
struct page *page);
+int finish_fault(struct vm_fault *vmf);
#endif
/*
diff -puN mm/memory.c~mm-factor-out-functionality-to-finish-page-faults mm/memory.c
--- a/mm/memory.c~mm-factor-out-functionality-to-finish-page-faults
+++ a/mm/memory.c
@@ -3074,6 +3074,38 @@ fault_handled:
return ret;
}
+
+/**
+ * finish_fault - finish page fault once we have prepared the page to fault
+ *
+ * @vmf: structure describing the fault
+ *
+ * This function handles all that is needed to finish a page fault once the
+ * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
+ * given page, adds reverse page mapping, handles memcg charges and LRU
+ * addition. The function returns 0 on success, VM_FAULT_ code in case of
+ * error.
+ *
+ * The function expects the page to be locked and on success it consumes a
+ * reference of a page being mapped (for the PTE which maps it).
+ */
+int finish_fault(struct vm_fault *vmf)
+{
+ struct page *page;
+ int ret;
+
+ /* Did we COW the page? */
+ if ((vmf->flags & FAULT_FLAG_WRITE) &&
+ !(vmf->vma->vm_flags & VM_SHARED))
+ page = vmf->cow_page;
+ else
+ page = vmf->page;
+ ret = alloc_set_pte(vmf, vmf->memcg, page);
+ if (vmf->pte)
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ return ret;
+}
+
static unsigned long fault_around_bytes __read_mostly =
rounddown_pow_of_two(65536);
@@ -3213,9 +3245,7 @@ static int do_read_fault(struct vm_fault
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
return ret;
- ret |= alloc_set_pte(vmf, NULL, vmf->page);
- if (vmf->pte)
- pte_unmap_unlock(vmf->pte, vmf->ptl);
+ ret |= finish_fault(vmf);
unlock_page(vmf->page);
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
put_page(vmf->page);
@@ -3250,9 +3280,7 @@ static int do_cow_fault(struct vm_fault
copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
__SetPageUptodate(vmf->cow_page);
- ret |= alloc_set_pte(vmf, vmf->memcg, vmf->cow_page);
- if (vmf->pte)
- pte_unmap_unlock(vmf->pte, vmf->ptl);
+ ret |= finish_fault(vmf);
if (!(ret & VM_FAULT_DAX_LOCKED)) {
unlock_page(vmf->page);
put_page(vmf->page);
@@ -3293,9 +3321,7 @@ static int do_shared_fault(struct vm_fau
}
}
- ret |= alloc_set_pte(vmf, NULL, vmf->page);
- if (vmf->pte)
- pte_unmap_unlock(vmf->pte, vmf->ptl);
+ ret |= finish_fault(vmf);
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
VM_FAULT_RETRY))) {
unlock_page(vmf->page);
_
Patches currently in -mm which might be from jack@xxxxxxx are
mm-join-struct-fault_env-and-vm_fault.patch
mm-use-vmf-address-instead-of-of-vmf-virtual_address.patch
mm-use-pgoff-in-struct-vm_fault-instead-of-passing-it-separately.patch
mm-use-passed-vm_fault-structure-in-__do_fault.patch
mm-trim-__do_fault-arguments.patch
mm-use-passed-vm_fault-structure-for-in-wp_pfn_shared.patch
mm-add-orig_pte-field-into-vm_fault.patch
mm-allow-full-handling-of-cow-faults-in-fault-handlers.patch
mm-factor-out-functionality-to-finish-page-faults.patch
mm-move-handling-of-cow-faults-into-dax-code.patch
mm-factor-out-common-parts-of-write-fault-handling.patch
mm-pass-vm_fault-structure-into-do_page_mkwrite.patch
mm-use-vmf-page-during-wp-faults.patch
mm-move-part-of-wp_page_reuse-into-the-single-call-site.patch
mm-provide-helper-for-finishing-mkwrite-faults.patch
mm-change-return-values-of-finish_mkwrite_fault.patch
mm-export-follow_pte.patch
dax-make-cache-flushing-protected-by-entry-lock.patch
dax-protect-pte-modification-on-wp-fault-by-radix-tree-entry-lock.patch
dax-clear-dirty-entry-tags-on-cache-flush.patch
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