The patch titled
Subject: mm/debug_vm_pgtable: remove pte entry from the page table
has been added to the -mm tree. Its filename is
mm-debug_vm_pgtable-remove-pte-entry-from-the-page-table.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-debug_vm_pgtable-remove-pte-entry-from-the-page-table.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-debug_vm_pgtable-remove-pte-entry-from-the-page-table.patch
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------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Subject: mm/debug_vm_pgtable: remove pte entry from the page table
Patch series "page table check fixes and cleanups", v4.
Two fixes:
mm/debug_vm_pgtable: remove pte entry from the page table
- remove a pte entry from the page table at the end of
debug_vm_pgtable pte test
mm/khugepaged: unify collapse pmd clear, flush and free
mm/page_table_check: check entries at pmd levels
- check pmd level in page_table_check for PTE regular entries
prior to freeing.
repro.c: https://gist.github.com/soleen/fdcd501d5df103976245fe84e9535087
config: https://gist.github.com/soleen/8a56f923c2fea9ce9c75b4e2517d4162
qemu_script: https://gist.github.com/soleen/f4be4795826b7ab1a51ae659582e179c
base image:
https://storage.googleapis.com/syzkaller/wheezy.img
https://storage.googleapis.com/syzkaller/wheezy.img.key
Small cleanup:
mm/page_table_check: use unsigned long for page counters and cleanup
This patch (of 4):
The pte entry that is used in pte_advanced_tests() is never removed from
the page table at the end of the test.
The issue is detected by page_table_check, to repro compile kernel with
the following configs:
CONFIG_DEBUG_VM_PGTABLE=y
CONFIG_PAGE_TABLE_CHECK=y
CONFIG_PAGE_TABLE_CHECK_ENFORCED=y
During the boot the following BUG is printed:
[ 2.262821] debug_vm_pgtable: [debug_vm_pgtable ]: Validating
architecture page table helpers
[ 2.276826] ------------[ cut here ]------------
[ 2.280426] kernel BUG at mm/page_table_check.c:162!
[ 2.284118] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[ 2.287787] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
5.16.0-11413-g2c271fe77d52 #3
[ 2.293226] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org
04/01/2014
...
The entry should be properly removed from the page table before the page
is released to the free list.
Link: https://lkml.kernel.org/r/20220126183637.1840960-2-pasha.tatashin@xxxxxxxxxx
Fixes: a5c3b9ffb0f4 ("mm/debug_vm_pgtable: add tests validating advanced arch page table helpers")
Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Tested-by: Zi Yan <ziy@xxxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Paul Turner <pjt@xxxxxxxxxx>
Cc: Wei Xu <weixugc@xxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Jiri Slaby <jirislaby@xxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [5.9+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/debug_vm_pgtable.c | 2 ++
1 file changed, 2 insertions(+)
--- a/mm/debug_vm_pgtable.c~mm-debug_vm_pgtable-remove-pte-entry-from-the-page-table
+++ a/mm/debug_vm_pgtable.c
@@ -171,6 +171,8 @@ static void __init pte_advanced_tests(st
ptep_test_and_clear_young(args->vma, args->vaddr, args->ptep);
pte = ptep_get(args->ptep);
WARN_ON(pte_young(pte));
+
+ ptep_get_and_clear_full(args->mm, args->vaddr, args->ptep, 1);
}
static void __init pte_savedwrite_tests(struct pgtable_debug_args *args)
_
Patches currently in -mm which might be from pasha.tatashin@xxxxxxxxxx are
mm-debug_vm_pgtable-remove-pte-entry-from-the-page-table.patch
mm-page_table_check-use-unsigned-long-for-page-counters-and-cleanup.patch
mm-khugepaged-unify-collapse-pmd-clear-flush-and-free.patch
mm-page_table_check-check-entries-at-pmd-levels.patch
