From: akpm@linux-foundation.org
To: aneesh.kumar@linux.ibm.com, corbet@lwn.net,
dave.hansen@linux.intel.com, frederic@kernel.org,
gthelen@google.com, hpa@zytor.com, jirislaby@kernel.org,
keescook@chromium.org, masahiroy@kernel.org, mingo@redhat.com,
mm-commits@vger.kernel.org, pasha.tatashin@soleen.com,
peterz@infradead.org, pjt@google.com, rientjes@google.com,
rppt@kernel.org, samitolvanen@google.com,
songmuchun@bytedance.com, tglx@linutronix.de, weixugc@google.com,
will@kernel.org
Subject: + mm-ptep_clear-page-table-helper.patch added to -mm tree
Date: Tue, 07 Dec 2021 16:05:22 -0800 [thread overview]
Message-ID: <20211208000522.HZ2fFQ0Go%akpm@linux-foundation.org> (raw)
The patch titled
Subject: mm: ptep_clear() page table helper
has been added to the -mm tree. Its filename is
mm-ptep_clear-page-table-helper.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-ptep_clear-page-table-helper.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-ptep_clear-page-table-helper.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin@soleen.com>
Subject: mm: ptep_clear() page table helper
We have ptep_get_and_clear() and ptep_get_and_clear_full() helpers to
clear PTE from user page tables, but there is no variant for simple clear
of a present PTE from user page tables without using a low level
pte_clear() which can be either native or para-virtualised.
Add a new ptep_clear() that can be used in common code to clear PTEs from
page table. We will need this call later in order to add a hook for page
table check.
Link: https://lkml.kernel.org/r/20211204182314.1470076-3-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Greg Thelen <gthelen@google.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wei Xu <weixugc@google.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
Documentation/vm/arch_pgtable_helpers.rst | 6 ++++--
include/linux/pgtable.h | 8 ++++++++
mm/debug_vm_pgtable.c | 2 +-
mm/khugepaged.c | 12 ++----------
4 files changed, 15 insertions(+), 13 deletions(-)
--- a/Documentation/vm/arch_pgtable_helpers.rst~mm-ptep_clear-page-table-helper
+++ a/Documentation/vm/arch_pgtable_helpers.rst
@@ -66,9 +66,11 @@ PTE Page Table Helpers
+---------------------------+--------------------------------------------------+
| pte_mknotpresent | Invalidates a mapped PTE |
+---------------------------+--------------------------------------------------+
-| ptep_get_and_clear | Clears a PTE |
+| ptep_clear | Clears a PTE |
+---------------------------+--------------------------------------------------+
-| ptep_get_and_clear_full | Clears a PTE |
+| ptep_get_and_clear | Clears and returns PTE |
++---------------------------+--------------------------------------------------+
+| ptep_get_and_clear_full | Clears and returns PTE (batched PTE unmap) |
+---------------------------+--------------------------------------------------+
| ptep_test_and_clear_young | Clears young from a PTE |
+---------------------------+--------------------------------------------------+
--- a/include/linux/pgtable.h~mm-ptep_clear-page-table-helper
+++ a/include/linux/pgtable.h
@@ -258,6 +258,14 @@ static inline int pmdp_clear_flush_young
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif
+#ifndef __HAVE_ARCH_PTEP_CLEAR
+static inline void ptep_clear(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep)
+{
+ pte_clear(mm, addr, ptep);
+}
+#endif
+
#ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR
static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
unsigned long address,
--- a/mm/debug_vm_pgtable.c~mm-ptep_clear-page-table-helper
+++ a/mm/debug_vm_pgtable.c
@@ -652,7 +652,7 @@ static void __init pte_clear_tests(struc
set_pte_at(args->mm, args->vaddr, args->ptep, pte);
flush_dcache_page(page);
barrier();
- pte_clear(args->mm, args->vaddr, args->ptep);
+ ptep_clear(args->mm, args->vaddr, args->ptep);
pte = ptep_get(args->ptep);
WARN_ON(!pte_none(pte));
}
--- a/mm/khugepaged.c~mm-ptep_clear-page-table-helper
+++ a/mm/khugepaged.c
@@ -756,11 +756,7 @@ static void __collapse_huge_page_copy(pt
* ptl mostly unnecessary.
*/
spin_lock(ptl);
- /*
- * paravirt calls inside pte_clear here are
- * superfluous.
- */
- pte_clear(vma->vm_mm, address, _pte);
+ ptep_clear(vma->vm_mm, address, _pte);
spin_unlock(ptl);
}
} else {
@@ -774,11 +770,7 @@ static void __collapse_huge_page_copy(pt
* inside page_remove_rmap().
*/
spin_lock(ptl);
- /*
- * paravirt calls inside pte_clear here are
- * superfluous.
- */
- pte_clear(vma->vm_mm, address, _pte);
+ ptep_clear(vma->vm_mm, address, _pte);
page_remove_rmap(src_page, false);
spin_unlock(ptl);
free_page_and_swap_cache(src_page);
_
Patches currently in -mm which might be from pasha.tatashin@soleen.com are
mm-change-page-type-prior-to-adding-page-table-entry.patch
mm-ptep_clear-page-table-helper.patch
mm-page-table-check.patch
x86-mm-add-x86_64-support-for-page-table-check.patch
next reply other threads:[~2021-12-08 0:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-08 0:05 akpm [this message]
-- strict thread matches above, loose matches on Subject: below --
2021-12-21 21:49 + mm-ptep_clear-page-table-helper.patch added to -mm tree akpm
2021-11-24 0:01 akpm
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