linux-toradex.git/mm/debug_vm_pgtable.c, branch v6.17-rc1

mm/debug_vm_pgtable: use a swp_entry_t input value for swap tests

2025-07-13T23:38:21+00:00

The various __pte/pmd_to_swp_entry and __swp_entry_to_pte/pmd helper
functions are expected to operate on swap PTE/PMD entries, not on present
and mapped entries.

Reflect this in the swap tests by using a swp_entry_t as input value, and
convert it to a swap PTE/PMD for testing, similar to how it is already
done in pte_swap_exclusive_tests().  Move the swap entry creation from
there to init_args() and store it in args, so it can also be used in other
functions.

The pte/pmd_swap_tests() are also changed to compare entries instead of
pfn values, again similar to pte_swap_exclusive_tests().  pte/pmd_pfn()
helpers are also not expected to operate on swap PTE/PMD entries at all.

Also update documentation, to reflect that the helpers operate on swap
PTE/PMD entries and not present and mapped entries, and use correct names,
i.e.  __swp_to_pte/pmd_entry -> __swp_entry_to_pte/pmd.

For consistency, also change pte/pmd_swap_soft_dirty_tests() to use
args->swp_entry instead of a present and mapped PTE/PMD.

Link: https://lore.kernel.org/all/20250623184321.927418-1-gerald.schaefer@linux.ibm.com
Link: https://lkml.kernel.org/r/20250630164726.930405-1-gerald.schaefer@linux.ibm.com
Signed-off-by: Gerald Schaefer 
Acked-by: David Hildenbrand 
Reviewed-by: Anshuman Khandual 
Cc: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton

mm: remove callers of pfn_t functionality

2025-07-10T05:42:19+00:00

All PFN_* pfn_t flags have been removed.  Therefore there is no longer a
need for the pfn_t type and all uses can be replaced with normal pfns.

Link: https://lkml.kernel.org/r/bbedfa576c9822f8032494efbe43544628698b1f.1750323463.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Acked-by: David Hildenbrand 
Cc: Balbir Singh 
Cc: Björn Töpel 
Cc: Björn Töpel 
Cc: Chunyan Zhang 
Cc: Dan Williams 
Cc: Deepak Gupta 
Cc: Gerald Schaefer 
Cc: Inki Dae 
Cc: John Groves 
Cc: John Hubbard 
Cc: Lorenzo Stoakes 
Cc: Matthew Wilcox (Oracle) 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

mm: remove devmap related functions and page table bits

2025-07-10T05:42:18+00:00

Now that DAX and all other reference counts to ZONE_DEVICE pages are
managed normally there is no need for the special devmap PTE/PMD/PUD page
table bits.  So drop all references to these, freeing up a software
defined page table bit on architectures supporting it.

Link: https://lkml.kernel.org/r/6389398c32cc9daa3dfcaa9f79c7972525d310ce.1750323463.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple 
Acked-by: Will Deacon  # arm64
Acked-by: David Hildenbrand 
Suggested-by: Chunyan Zhang 
Reviewed-by: Björn Töpel 
Reviewed-by: Jason Gunthorpe 
Cc: Balbir Singh 
Cc: Björn Töpel 
Cc: Christoph Hellwig 
Cc: Dan Williams 
Cc: Deepak Gupta 
Cc: Gerald Schaefer 
Cc: Inki Dae 
Cc: John Groves 
Cc: John Hubbard 
Cc: Lorenzo Stoakes 
Cc: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton

mm: remove mk_huge_pte()

2025-05-12T00:48:04+00:00

The only remaining user of mk_huge_pte() is the debug code, so remove the
API and replace its use with pfn_pte() which lets us remove the conversion
to a page first.  We should always call arch_make_huge_pte() to turn this
PTE into a huge PTE before operating on it with huge_pte_mkdirty() etc.

Link: https://lkml.kernel.org/r/20250402181709.2386022-10-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Cc: Zi Yan 
Cc: Alexander Gordeev 
Cc: Andreas Larsson 
Cc: Anton Ivanov 
Cc: Dave Hansen 
Cc: David Hildenbrand 
Cc: "David S. Miller" 
Cc: Geert Uytterhoeven 
Cc: Johannes Berg 
Cc: Muchun Song 
Cc: Richard Weinberger 
Cc: 
Signed-off-by: Andrew Morton

mm/debug_vm_pgtable: Use pxdp_get() for accessing page table entries

2024-09-17T08:07:01+00:00

This replaces all the existing READ_ONCE() based page table accesses with
respective pxdp_get() helpers. Although these helpers might also fallback
to READ_ONCE() as default, but they do provide an opportunity for various
platforms to override when required. This change is a step in direction to
replace all page table entry accesses with respective pxdp_get() helpers.

Link: https://lkml.kernel.org/r/20240910115746.514454-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual 
Acked-by: David Hildenbrand 
Cc: Ryan Roberts 
Signed-off-by: Andrew Morton

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