linux.git/mm/debug_vm_pgtable.c, branch v6.10-rc6

mm/debug_vm_pgtable: drop RANDOM_ORVALUE trick

2024-06-15T17:43:08+00:00

Macro RANDOM_ORVALUE was used to make sure the pgtable entry will be
populated with !none data in clear tests.

The RANDOM_ORVALUE tried to cover mostly all the bits in a pgtable entry,
even if there's no discussion on whether all the bits will be vaild.  Both
S390 and PPC64 have their own masks to avoid touching some bits.  Now it's
the turn for x86_64.

The issue is there's a recent report from Mikhail Gavrilov showing that
this can cause a warning with the newly added pte set check in commit
8430557fc5 on writable v.s.  userfaultfd-wp bit, even though the check
itself was valid, the random pte is not.  We can choose to mask more bits
out.

However the need to have such random bits setup is questionable, as now
it's already guaranteed to be true on below:

  - For pte level, the pgtable entry will be installed with value from
    pfn_pte(), where pfn points to a valid page.  Hence the pte will be
    !none already if populated with pfn_pte().

  - For upper-than-pte level, the pgtable entry should contain a directory
    entry always, which is also !none.

All the cases look like good enough to test a pxx_clear() helper.  Instead
of extending the bitmask, drop the "set random bits" trick completely.  Add
some warning guards to make sure the entries will be !none before clear().

Link: https://lkml.kernel.org/r/20240523132139.289719-1-peterx@redhat.com
Fixes: 8430557fc584 ("mm/page_table_check: support userfault wr-protect entries")
Signed-off-by: Peter Xu 
Reported-by: Mikhail Gavrilov 
Link: https://lore.kernel.org/r/CABXGCsMB9A8-X+Np_Q+fWLURYL_0t3Y-MdoNabDM-Lzk58-DGA@mail.gmail.com
Tested-by: Mikhail Gavrilov 
Reviewed-by: Pasha Tatashin 
Acked-by: David Hildenbrand 
Cc: Aneesh Kumar K.V 
Cc: Gavin Shan 
Cc: Anshuman Khandual 
Signed-off-by: Andrew Morton

mm/debug_vm_pgtable: test pmd_leaf() behavior with pmd_mkinvalid()

2024-05-07T17:37:00+00:00

An invalidated pmd should still cause pmd_leaf() to return true.  Let's
test for that to ensure all arches remain consistent.

Link: https://lkml.kernel.org/r/20240501144439.1389048-1-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts 
Reviewed-by: Anshuman Khandual 
Reviewed-by: David Hildenbrand 
Cc: Catalin Marinas 
Signed-off-by: Andrew Morton

fix missing vmalloc.h includes

2024-04-26T03:55:49+00:00

Patch series "Memory allocation profiling", v6.

Overview:
Low overhead [1] per-callsite memory allocation profiling. Not just for
debug kernels, overhead low enough to be deployed in production.

Example output:
  root@moria-kvm:~# sort -rn /proc/allocinfo
   127664128    31168 mm/page_ext.c:270 func:alloc_page_ext
    56373248     4737 mm/slub.c:2259 func:alloc_slab_page
    14880768     3633 mm/readahead.c:247 func:page_cache_ra_unbounded
    14417920     3520 mm/mm_init.c:2530 func:alloc_large_system_hash
    13377536      234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs
    11718656     2861 mm/filemap.c:1919 func:__filemap_get_folio
     9192960     2800 kernel/fork.c:307 func:alloc_thread_stack_node
     4206592        4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable
     4136960     1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start
     3940352      962 mm/memory.c:4214 func:alloc_anon_folio
     2894464    22613 fs/kernfs/dir.c:615 func:__kernfs_new_node
     ...

Usage:
kconfig options:
 - CONFIG_MEM_ALLOC_PROFILING
 - CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
 - CONFIG_MEM_ALLOC_PROFILING_DEBUG
   adds warnings for allocations that weren't accounted because of a
   missing annotation

sysctl:
  /proc/sys/vm/mem_profiling

Runtime info:
  /proc/allocinfo

Notes:

[1]: Overhead
To measure the overhead we are comparing the following configurations:
(1) Baseline with CONFIG_MEMCG_KMEM=n
(2) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n)
(3) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y)
(4) Enabled at runtime (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n && /proc/sys/vm/mem_profiling=1)
(5) Baseline with CONFIG_MEMCG_KMEM=y && allocating with __GFP_ACCOUNT
(6) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n)  && CONFIG_MEMCG_KMEM=y
(7) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y) && CONFIG_MEMCG_KMEM=y

Performance overhead:
To evaluate performance we implemented an in-kernel test executing
multiple get_free_page/free_page and kmalloc/kfree calls with allocation
sizes growing from 8 to 240 bytes with CPU frequency set to max and CPU
affinity set to a specific CPU to minimize the noise. Below are results
from running the test on Ubuntu 22.04.2 LTS with 6.8.0-rc1 kernel on
56 core Intel Xeon:

                        kmalloc                 pgalloc
(1 baseline)            6.764s                  16.902s
(2 default disabled)    6.793s  (+0.43%)        17.007s (+0.62%)
(3 default enabled)     7.197s  (+6.40%)        23.666s (+40.02%)
(4 runtime enabled)     7.405s  (+9.48%)        23.901s (+41.41%)
(5 memcg)               13.388s (+97.94%)       48.460s (+186.71%)
(6 def disabled+memcg)  13.332s (+97.10%)       48.105s (+184.61%)
(7 def enabled+memcg)   13.446s (+98.78%)       54.963s (+225.18%)

Memory overhead:
Kernel size:

   text           data        bss         dec         diff
(1) 26515311	      18890222    17018880    62424413
(2) 26524728	      19423818    16740352    62688898    264485
(3) 26524724	      19423818    16740352    62688894    264481
(4) 26524728	      19423818    16740352    62688898    264485
(5) 26541782	      18964374    16957440    62463596    39183

Memory consumption on a 56 core Intel CPU with 125GB of memory:
Code tags:           192 kB
PageExts:         262144 kB (256MB)
SlabExts:           9876 kB (9.6MB)
PcpuExts:            512 kB (0.5MB)

Total overhead is 0.2% of total memory.

Benchmarks:

Hackbench tests run 100 times:
hackbench -s 512 -l 200 -g 15 -f 25 -P
      baseline       disabled profiling           enabled profiling
avg   0.3543         0.3559 (+0.0016)             0.3566 (+0.0023)
stdev 0.0137         0.0188                       0.0077


hackbench -l 10000
      baseline       disabled profiling           enabled profiling
avg   6.4218         6.4306 (+0.0088)             6.5077 (+0.0859)
stdev 0.0933         0.0286                       0.0489

stress-ng tests:
stress-ng --class memory --seq 4 -t 60
stress-ng --class cpu --seq 4 -t 60
Results posted at: https://evilpiepirate.org/~kent/memalloc_prof_v4_stress-ng/

[2] https://lore.kernel.org/all/20240306182440.2003814-1-surenb@google.com/


This patch (of 37):

The next patch drops vmalloc.h from a system header in order to fix a
circular dependency; this adds it to all the files that were pulling it in
implicitly.

[kent.overstreet@linux.dev: fix arch/alpha/lib/memcpy.c]
  Link: https://lkml.kernel.org/r/20240327002152.3339937-1-kent.overstreet@linux.dev
[surenb@google.com: fix arch/x86/mm/numa_32.c]
  Link: https://lkml.kernel.org/r/20240402180933.1663992-1-surenb@google.com
[kent.overstreet@linux.dev: a few places were depending on sizes.h]
  Link: https://lkml.kernel.org/r/20240404034744.1664840-1-kent.overstreet@linux.dev
[arnd@arndb.de: fix mm/kasan/hw_tags.c]
  Link: https://lkml.kernel.org/r/20240404124435.3121534-1-arnd@kernel.org
[surenb@google.com: fix arc build]
  Link: https://lkml.kernel.org/r/20240405225115.431056-1-surenb@google.com
Link: https://lkml.kernel.org/r/20240321163705.3067592-1-surenb@google.com
Link: https://lkml.kernel.org/r/20240321163705.3067592-2-surenb@google.com
Signed-off-by: Kent Overstreet 
Signed-off-by: Suren Baghdasaryan 
Signed-off-by: Arnd Bergmann 
Reviewed-by: Pasha Tatashin 
Tested-by: Kees Cook 
Cc: Alexander Viro 
Cc: Alex Gaynor 
Cc: Alice Ryhl 
Cc: Andreas Hindborg 
Cc: Benno Lossin 
Cc: "Björn Roy Baron" 
Cc: Boqun Feng 
Cc: Christoph Lameter 
Cc: Dennis Zhou 
Cc: Gary Guo 
Cc: Miguel Ojeda 
Cc: Peter Zijlstra 
Cc: Tejun Heo 
Cc: Vlastimil Babka 
Cc: Wedson Almeida Filho 
Signed-off-by: Andrew Morton

mm/debug_vm_pgtable: fix BUG_ON with pud advanced test

2024-02-24T01:27:13+00:00

Architectures like powerpc add debug checks to ensure we find only devmap
PUD pte entries.  These debug checks are only done with CONFIG_DEBUG_VM. 
This patch marks the ptes used for PUD advanced test devmap pte entries so
that we don't hit on debug checks on architecture like ppc64 as below.

WARNING: CPU: 2 PID: 1 at arch/powerpc/mm/book3s64/radix_pgtable.c:1382 radix__pud_hugepage_update+0x38/0x138
....
NIP [c0000000000a7004] radix__pud_hugepage_update+0x38/0x138
LR [c0000000000a77a8] radix__pudp_huge_get_and_clear+0x28/0x60
Call Trace:
[c000000004a2f950] [c000000004a2f9a0] 0xc000000004a2f9a0 (unreliable)
[c000000004a2f980] [000d34c100000000] 0xd34c100000000
[c000000004a2f9a0] [c00000000206ba98] pud_advanced_tests+0x118/0x334
[c000000004a2fa40] [c00000000206db34] debug_vm_pgtable+0xcbc/0x1c48
[c000000004a2fc10] [c00000000000fd28] do_one_initcall+0x60/0x388

Also

 kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:202!
 ....

 NIP [c000000000096510] pudp_huge_get_and_clear_full+0x98/0x174
 LR [c00000000206bb34] pud_advanced_tests+0x1b4/0x334
 Call Trace:
 [c000000004a2f950] [000d34c100000000] 0xd34c100000000 (unreliable)
 [c000000004a2f9a0] [c00000000206bb34] pud_advanced_tests+0x1b4/0x334
 [c000000004a2fa40] [c00000000206db34] debug_vm_pgtable+0xcbc/0x1c48
 [c000000004a2fc10] [c00000000000fd28] do_one_initcall+0x60/0x388

Link: https://lkml.kernel.org/r/20240129060022.68044-1-aneesh.kumar@kernel.org
Fixes: 27af67f35631 ("powerpc/book3s64/mm: enable transparent pud hugepage")
Signed-off-by: Aneesh Kumar K.V (IBM) 
Cc: Anshuman Khandual 
Cc: Michael Ellerman 
Cc: 
Signed-off-by: Andrew Morton

mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER

2024-01-08T23:27:15+00:00

commit 23baf831a32c ("mm, treewide: redefine MAX_ORDER sanely") has
changed the definition of MAX_ORDER to be inclusive.  This has caused
issues with code that was not yet upstream and depended on the previous
definition.

To draw attention to the altered meaning of the define, rename MAX_ORDER
to MAX_PAGE_ORDER.

Link: https://lkml.kernel.org/r/20231228144704.14033-2-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov 
Cc: Linus Torvalds 
Signed-off-by: Andrew Morton

mm: fix multiple typos in multiple files

2023-10-25T23:47:14+00:00

Link: https://lkml.kernel.org/r/20231023124405.36981-1-m.muzzammilashraf@gmail.com
Signed-off-by: Muhammad Muzammil 
Reviewed-by: Randy Dunlap 
Cc: "James E.J. Bottomley" 
Cc: Matthew Wilcox (Oracle) 
Cc: Muhammad Muzammil 
Signed-off-by: Andrew Morton

Merge tag 'x86_shstk_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-08-31T19:20:12+00:00

Pull x86 shadow stack support from Dave Hansen:
 "This is the long awaited x86 shadow stack support, part of Intel's
  Control-flow Enforcement Technology (CET).

  CET consists of two related security features: shadow stacks and
  indirect branch tracking. This series implements just the shadow stack
  part of this feature, and just for userspace.

  The main use case for shadow stack is providing protection against
  return oriented programming attacks. It works by maintaining a
  secondary (shadow) stack using a special memory type that has
  protections against modification. When executing a CALL instruction,
  the processor pushes the return address to both the normal stack and
  to the special permission shadow stack. Upon RET, the processor pops
  the shadow stack copy and compares it to the normal stack copy.

  For more information, refer to the links below for the earlier
  versions of this patch set"

Link: https://lore.kernel.org/lkml/20220130211838.8382-1-rick.p.edgecombe@intel.com/
Link: https://lore.kernel.org/lkml/20230613001108.3040476-1-rick.p.edgecombe@intel.com/

* tag 'x86_shstk_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (47 commits)
  x86/shstk: Change order of __user in type
  x86/ibt: Convert IBT selftest to asm
  x86/shstk: Don't retry vm_munmap() on -EINTR
  x86/kbuild: Fix Documentation/ reference
  x86/shstk: Move arch detail comment out of core mm
  x86/shstk: Add ARCH_SHSTK_STATUS
  x86/shstk: Add ARCH_SHSTK_UNLOCK
  x86: Add PTRACE interface for shadow stack
  selftests/x86: Add shadow stack test
  x86/cpufeatures: Enable CET CR4 bit for shadow stack
  x86/shstk: Wire in shadow stack interface
  x86: Expose thread features in /proc/$PID/status
  x86/shstk: Support WRSS for userspace
  x86/shstk: Introduce map_shadow_stack syscall
  x86/shstk: Check that signal frame is shadow stack mem
  x86/shstk: Check that SSP is aligned on sigreturn
  x86/shstk: Handle signals for shadow stack
  x86/shstk: Introduce routines modifying shstk
  x86/shstk: Handle thread shadow stack
  x86/shstk: Add user-mode shadow stack support
  ...

mm: change pudp_huge_get_and_clear_full take vm_area_struct as arg

2023-08-18T17:12:53+00:00

We will use this in a later patch to do tlb flush when clearing pud
entries on powerpc.  This is similar to commit 93a98695f2f9 ("mm: change
pmdp_huge_get_and_clear_full take vm_area_struct as arg")

Link: https://lkml.kernel.org/r/20230724190759.483013-3-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V 
Reviewed-by: Christophe Leroy 
Cc: Catalin Marinas 
Cc: Dan Williams 
Cc: Joao Martins 
Cc: Michael Ellerman 
Cc: Mike Kravetz 
Cc: Muchun Song 
Cc: Nicholas Piggin 
Cc: Oscar Salvador 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

mm/hugepage pud: allow arch-specific helper function to check huge page pud support

2023-08-18T17:12:53+00:00

Patch series "Add support for DAX vmemmap optimization for ppc64", v6.

This patch series implements changes required to support DAX vmemmap
optimization for ppc64.  The vmemmap optimization is only enabled with
radix MMU translation and 1GB PUD mapping with 64K page size.

The patch series also splits the hugetlb vmemmap optimization as a
separate Kconfig variable so that architectures can enable DAX vmemmap
optimization without enabling hugetlb vmemmap optimization.  This should
enable architectures like arm64 to enable DAX vmemmap optimization while
they can't enable hugetlb vmemmap optimization.  More details of the same
are in patch "mm/vmemmap optimization: Split hugetlb and devdax vmemmap
optimization".

With 64K page size for 16384 pages added (1G) we save 14 pages
With 4K page size for 262144 pages added (1G) we save 4094 pages
With 4K page size for 512 pages added (2M) we save 6 pages


This patch (of 13):

Architectures like powerpc would like to enable transparent huge page pud
support only with radix translation.  To support that add
has_transparent_pud_hugepage() helper that architectures can override.

[aneesh.kumar@linux.ibm.com: use the new has_transparent_pud_hugepage()]
  Link: https://lkml.kernel.org/r/87tttrvtaj.fsf@linux.ibm.com
Link: https://lkml.kernel.org/r/20230724190759.483013-1-aneesh.kumar@linux.ibm.com
Link: https://lkml.kernel.org/r/20230724190759.483013-2-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V 
Reviewed-by: Christophe Leroy 
Cc: Catalin Marinas 
Cc: Dan Williams 
Cc: Joao Martins 
Cc: Michael Ellerman 
Cc: Mike Kravetz 
Cc: Muchun Song 
Cc: Nicholas Piggin 
Cc: Oscar Salvador 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

mm: Make pte_mkwrite() take a VMA

2023-07-11T21:12:15+00:00

The x86 Shadow stack feature includes a new type of memory called shadow
stack. This shadow stack memory has some unusual properties, which requires
some core mm changes to function properly.

One of these unusual properties is that shadow stack memory is writable,
but only in limited ways. These limits are applied via a specific PTE
bit combination. Nevertheless, the memory is writable, and core mm code
will need to apply the writable permissions in the typical paths that
call pte_mkwrite(). Future patches will make pte_mkwrite() take a VMA, so
that the x86 implementation of it can know whether to create regular
writable or shadow stack mappings.

But there are a couple of challenges to this. Modifying the signatures of
each arch pte_mkwrite() implementation would be error prone because some
are generated with macros and would need to be re-implemented. Also, some
pte_mkwrite() callers operate on kernel memory without a VMA.

So this can be done in a three step process. First pte_mkwrite() can be
renamed to pte_mkwrite_novma() in each arch, with a generic pte_mkwrite()
added that just calls pte_mkwrite_novma(). Next callers without a VMA can
be moved to pte_mkwrite_novma(). And lastly, pte_mkwrite() and all callers
can be changed to take/pass a VMA.

Previous work pte_mkwrite() renamed pte_mkwrite_novma() and converted
callers that don't have a VMA were to use pte_mkwrite_novma(). So now
change pte_mkwrite() to take a VMA and change the remaining callers to
pass a VMA. Apply the same changes for pmd_mkwrite().

No functional change.

Suggested-by: David Hildenbrand 
Signed-off-by: Rick Edgecombe 
Signed-off-by: Dave Hansen 
Reviewed-by: Mike Rapoport (IBM) 
Acked-by: David Hildenbrand 
Link: https://lore.kernel.org/all/20230613001108.3040476-4-rick.p.edgecombe%40intel.com