linux-toradex.git/mm/debug_vm_pgtable.c, branch v5.17-rc7

mm/debug_vm_pgtable: remove pte entry from the page table

2022-02-04T17:25:04+00:00

Patch series "page table check fixes and cleanups", v5.

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:

  debug_vm_pgtable: [debug_vm_pgtable         ]: Validating architecture page table helpers
  ------------[ cut here ]------------
  kernel BUG at mm/page_table_check.c:162!
  invalid opcode: 0000 [#1] PREEMPT SMP PTI
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.16.0-11413-g2c271fe77d52 #3
  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/20220131203249.2832273-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20220131203249.2832273-2-pasha.tatashin@soleen.com
Fixes: a5c3b9ffb0f4 ("mm/debug_vm_pgtable: add tests validating advanced arch page table helpers")
Signed-off-by: Pasha Tatashin 
Reviewed-by: Zi Yan 
Tested-by: Zi Yan 
Acked-by: David Rientjes 
Reviewed-by: Anshuman Khandual 
Cc: Paul Turner 
Cc: Wei Xu 
Cc: Greg Thelen 
Cc: Ingo Molnar 
Cc: Will Deacon 
Cc: Mike Rapoport 
Cc: Dave Hansen 
Cc: H. Peter Anvin 
Cc: Aneesh Kumar K.V 
Cc: Jiri Slaby 
Cc: Muchun Song 
Cc: Hugh Dickins 
Cc: 	[5.9+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: ptep_clear() page table helper

2022-01-15T14:30:28+00:00

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/20211221154650.1047963-3-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin 
Cc: Aneesh Kumar K.V 
Cc: Dave Hansen 
Cc: David Rientjes 
Cc: Frederic Weisbecker 
Cc: Greg Thelen 
Cc: "H. Peter Anvin" 
Cc: Hugh Dickins 
Cc: Ingo Molnar 
Cc: Jiri Slaby 
Cc: Jonathan Corbet 
Cc: Kees Cook 
Cc: Masahiro Yamada 
Cc: Mike Rapoport 
Cc: Muchun Song 
Cc: Paul Turner 
Cc: Peter Zijlstra 
Cc: Sami Tolvanen 
Cc: Thomas Gleixner 
Cc: Wei Xu 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/debug_vm_pgtable: update comments regarding migration swap entries

2022-01-15T14:30:26+00:00

Commit 4dd845b5a3e5 ("mm/swapops: rework swap entry manipulation code")
had changed migtation entry related helpers.  Just update
debug_vm_pgatble() synced documentation to reflect those changes.

Link: https://lkml.kernel.org/r/1641880417-24848-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual 
Cc: Jonathan Corbet 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: debug_vm_pgtable: don't use __P000 directly

2021-11-06T20:30:33+00:00

The __Pxxx/__Sxxx macros are only for protection_map[] init.  All usage
of them in linux should come from protection_map array.

Because a lot of architectures would re-initilize protection_map[]
array, eg: x86-mem_encrypt, m68k-motorola, mips, arm, sparc.

Using __P000 is not rigorous.

Link: https://lkml.kernel.org/r/20210924060821.1138281-1-guoren@kernel.org
Signed-off-by: Guo Ren 
Reviewed-by: Andrew Morton 
Reviewed-by: Anshuman Khandual 
Cc: Gavin Shan 
Cc: Christophe Leroy 
Cc: Gerald Schaefer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/debug_vm_pgtable: fix corrupted page flag

2021-09-03T16:58:10+00:00

In page table entry modifying tests, set_xxx_at() are used to populate
the page table entries. On ARM64, PG_arch_1 (PG_dcache_clean) flag is
set to the target page flag if execution permission is given. The logic
exits since commit 4f04d8f00545 ("arm64: MMU definitions"). The page
flag is kept when the page is free'd to buddy's free area list. However,
it will trigger page checking failure when it's pulled from the buddy's
free area list, as the following warning messages indicate.

   BUG: Bad page state in process memhog  pfn:08000
   page:0000000015c0a628 refcount:0 mapcount:0 \
        mapping:0000000000000000 index:0x1 pfn:0x8000
   flags: 0x7ffff8000000800(arch_1|node=0|zone=0|lastcpupid=0xfffff)
   raw: 07ffff8000000800 dead000000000100 dead000000000122 0000000000000000
   raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
   page dumped because: PAGE_FLAGS_CHECK_AT_PREP flag(s) set

This fixes the issue by clearing PG_arch_1 through flush_dcache_page()
after set_xxx_at() is called. For architectures other than ARM64, the
unexpected overhead of cache flushing is acceptable.

Link: https://lkml.kernel.org/r/20210809092631.1888748-13-gshan@redhat.com
Fixes: a5c3b9ffb0f4 ("mm/debug_vm_pgtable: add tests validating advanced arch page table helpers")
Signed-off-by: Gavin Shan 
Reviewed-by: Anshuman Khandual 
Tested-by: Christophe Leroy 	[powerpc 8xx]
Tested-by: Gerald Schaefer 	[s390]
Cc: Aneesh Kumar K.V 
Cc: Catalin Marinas 
Cc: Chunyu Hu 
Cc: Qian Cai 
Cc: Vineet Gupta 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/debug_vm_pgtable: remove unused code

2021-09-03T16:58:10+00:00

The variables used by old implementation isn't needed as we switched to
"struct pgtable_debug_args".  Lets remove them and related code in
debug_vm_pgtable().

Link: https://lkml.kernel.org/r/20210809092631.1888748-12-gshan@redhat.com
Signed-off-by: Gavin Shan 
Reviewed-by: Anshuman Khandual 
Tested-by: Christophe Leroy 	[powerpc 8xx]
Tested-by: Gerald Schaefer 	[s390]
Cc: Aneesh Kumar K.V 
Cc: Catalin Marinas 
Cc: Chunyu Hu 
Cc: Qian Cai 
Cc: Vineet Gupta 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/debug_vm_pgtable: use struct pgtable_debug_args in PGD and P4D modifying tests

2021-09-03T16:58:10+00:00

This uses struct pgtable_debug_args in PGD/P4D modifying tests.  No
allocated huge page is used in these tests.  Besides, the unused variable
@saved_p4dp and @saved_pudp are dropped.

Link: https://lkml.kernel.org/r/20210809092631.1888748-11-gshan@redhat.com
Signed-off-by: Gavin Shan 
Reviewed-by: Anshuman Khandual 
Tested-by: Christophe Leroy 	[powerpc 8xx]
Tested-by: Gerald Schaefer 	[s390]
Cc: Aneesh Kumar K.V 
Cc: Catalin Marinas 
Cc: Chunyu Hu 
Cc: Qian Cai 
Cc: Vineet Gupta 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/debug_vm_pgtable: use struct pgtable_debug_args in PUD modifying tests

2021-09-03T16:58:09+00:00

This uses struct pgtable_debug_args in PUD modifying tests.  The allocated
huge page is used when set_pud_at() is used.  The corresponding tests are
skipped if the huge page doesn't exist.  Besides, the following unused
variables in debug_vm_pgtable() are dropped: @prot, @paddr, @pud_aligned.

Link: https://lkml.kernel.org/r/20210809092631.1888748-10-gshan@redhat.com
Signed-off-by: Gavin Shan 
Reviewed-by: Anshuman Khandual 
Tested-by: Christophe Leroy 	[powerpc 8xx]
Tested-by: Gerald Schaefer 	[s390]
Cc: Aneesh Kumar K.V 
Cc: Catalin Marinas 
Cc: Chunyu Hu 
Cc: Qian Cai 
Cc: Vineet Gupta 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/debug_vm_pgtable: use struct pgtable_debug_args in PMD modifying tests

2021-09-03T16:58:09+00:00

This uses struct pgtable_debug_args in PMD modifying tests.  The allocated
huge page is used when set_pmd_at() is used.  The corresponding tests are
skipped if the huge page doesn't exist.  Besides, the unused variable
@pmd_aligned in debug_vm_pgtable() is dropped.

Link: https://lkml.kernel.org/r/20210809092631.1888748-9-gshan@redhat.com
Signed-off-by: Gavin Shan 
Reviewed-by: Anshuman Khandual 
Tested-by: Christophe Leroy 	[powerpc 8xx]
Tested-by: Gerald Schaefer 	[s390]
Cc: Aneesh Kumar K.V 
Cc: Catalin Marinas 
Cc: Chunyu Hu 
Cc: Qian Cai 
Cc: Vineet Gupta 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/debug_vm_pgtable: use struct pgtable_debug_args in PTE modifying tests

2021-09-03T16:58:09+00:00

This uses struct pgtable_debug_args in PTE modifying tests.  The allocated
page is used as set_pte_at() is used there.  The tests are skipped if the
allocated page doesn't exist.  It's notable that args->ptep need to be
mapped before the tests.  The reason why we don't map args->ptep at the
beginning is PTE entry is only mapped and accessible in atomic context
when CONFIG_HIGHPTE is enabled.  So we avoid to do that so that atomic
context is only enabled if needed.

Besides, the unused variable @pte_aligned and @ptep in debug_vm_pgtable()
are dropped.

Link: https://lkml.kernel.org/r/20210809092631.1888748-8-gshan@redhat.com
Signed-off-by: Gavin Shan 
Reviewed-by: Anshuman Khandual 
Tested-by: Christophe Leroy 	[powerpc 8xx]
Tested-by: Gerald Schaefer 	[s390]
Cc: Aneesh Kumar K.V 
Cc: Catalin Marinas 
Cc: Chunyu Hu 
Cc: Qian Cai 
Cc: Vineet Gupta 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds