This is a note to let you know that I've just added the patch titled
mm: add follow_pte_pmd()
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-add-follow_pte_pmd.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Jan 24 07:28:36 PM CET 2022
From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Date: Mon, 24 Jan 2022 17:41:12 +0100
Subject: mm: add follow_pte_pmd()
To: stable@xxxxxxxxxxxxxxx
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>, Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>, ". Andrew Morton" <akpm@xxxxxxxxxxxxxxxxxxxx>
Message-ID: <Ye7WqMoYNyxOqWId@xxxxxxxxxxxxxxx>
Content-Disposition: inline
From: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
commit 097963959594c5eccaba42510f7033f703211bda upstream.
Patch series "Write protect DAX PMDs in *sync path".
Currently dax_mapping_entry_mkclean() fails to clean and write protect
the pmd_t of a DAX PMD entry during an *sync operation. This can result
in data loss, as detailed in patch 2.
This series is based on Dan's "libnvdimm-pending" branch, which is the
current home for Jan's "dax: Page invalidation fixes" series. You can
find a working tree here:
https://git.kernel.org/cgit/linux/kernel/git/zwisler/linux.git/log/?h=dax_pmd_clean
This patch (of 2):
Similar to follow_pte(), follow_pte_pmd() allows either a PTE leaf or a
huge page PMD leaf to be found and returned.
Link: http://lkml.kernel.org/r/1482272586-21177-2-git-send-email-ross.zwisler@xxxxxxxxxxxxxxx
Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Suggested-by: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 4.9: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 2 ++
mm/memory.c | 37 ++++++++++++++++++++++++++++++-------
2 files changed, 32 insertions(+), 7 deletions(-)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1269,6 +1269,8 @@ int copy_page_range(struct mm_struct *ds
struct vm_area_struct *vma);
void unmap_mapping_range(struct address_space *mapping,
loff_t const holebegin, loff_t const holelen, int even_cows);
+int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
+ pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp);
int follow_pfn(struct vm_area_struct *vma, unsigned long address,
unsigned long *pfn);
int follow_phys(struct vm_area_struct *vma, unsigned long address,
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3780,8 +3780,8 @@ int __pmd_alloc(struct mm_struct *mm, pu
}
#endif /* __PAGETABLE_PMD_FOLDED */
-static int __follow_pte(struct mm_struct *mm, unsigned long address,
- pte_t **ptepp, spinlock_t **ptlp)
+static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
+ pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
{
pgd_t *pgd;
pud_t *pud;
@@ -3798,11 +3798,20 @@ static int __follow_pte(struct mm_struct
pmd = pmd_offset(pud, address);
VM_BUG_ON(pmd_trans_huge(*pmd));
- if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
- goto out;
- /* We cannot handle huge page PFN maps. Luckily they don't exist. */
- if (pmd_huge(*pmd))
+ if (pmd_huge(*pmd)) {
+ if (!pmdpp)
+ goto out;
+
+ *ptlp = pmd_lock(mm, pmd);
+ if (pmd_huge(*pmd)) {
+ *pmdpp = pmd;
+ return 0;
+ }
+ spin_unlock(*ptlp);
+ }
+
+ if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
goto out;
ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
@@ -3825,9 +3834,23 @@ static inline int follow_pte(struct mm_s
/* (void) is needed to make gcc happy */
(void) __cond_lock(*ptlp,
- !(res = __follow_pte(mm, address, ptepp, ptlp)));
+ !(res = __follow_pte_pmd(mm, address, ptepp, NULL,
+ ptlp)));
+ return res;
+}
+
+int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
+ pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
+{
+ int res;
+
+ /* (void) is needed to make gcc happy */
+ (void) __cond_lock(*ptlp,
+ !(res = __follow_pte_pmd(mm, address, ptepp, pmdpp,
+ ptlp)));
return res;
}
+EXPORT_SYMBOL(follow_pte_pmd);
/**
* follow_pfn - look up PFN at a user virtual address
Patches currently in stable-queue which might be from ben@xxxxxxxxxxxxxxx are
queue-4.9/lib-timerqueue-rely-on-rbtree-semantics-for-next-timer.patch
queue-4.9/gup-document-and-work-around-cow-can-break-either-way-issue.patch
queue-4.9/fuse-fix-live-lock-in-fuse_iget.patch
queue-4.9/kvm-do-not-assume-pte-is-writable-after-follow_pfn.patch
queue-4.9/drm-ttm-nouveau-don-t-call-tt-destroy-callback-on-alloc-failure.patch
queue-4.9/gianfar-simplify-fcs-handling-and-fix-memory-leak.patch
queue-4.9/mm-add-follow_pte_pmd.patch
queue-4.9/revert-gup-document-and-work-around-cow-can-break-either-way-issue.patch
queue-4.9/gianfar-fix-jumbo-packets-napi-rx-overrun-crash.patch
queue-4.9/cipso-calipso-resolve-a-number-of-problems-with-the-doi-refcounts.patch
queue-4.9/rbtree-cache-leftmost-node-internally.patch
queue-4.9/kvm-use-kvm_pfn_t-for-local-pfn-variable-in-hva_to_pfn_remapped.patch
queue-4.9/kvm-do-not-allow-mapping-valid-but-non-reference-counted-pages.patch
queue-4.9/fuse-fix-bad-inode.patch
