linux.git/lib/alloc_tag.c, branch v7.1-rc2

mm/alloc_tag: clear codetag for pages allocated before page_ext initialization

2026-04-18T07:10:50+00:00

Due to initialization ordering, page_ext is allocated and initialized
relatively late during boot.  Some pages have already been allocated and
freed before page_ext becomes available, leaving their codetag
uninitialized.

A clear example is in init_section_page_ext(): alloc_page_ext() calls
kmemleak_alloc().  If the slab cache has no free objects, it falls back to
the buddy allocator to allocate memory.  However, at this point page_ext
is not yet fully initialized, so these newly allocated pages have no
codetag set.  These pages may later be reclaimed by KASAN, which causes
the warning to trigger when they are freed because their codetag ref is
still empty.

Use a global array to track pages allocated before page_ext is fully
initialized.  The array size is fixed at 8192 entries, and will emit a
warning if this limit is exceeded.  When page_ext initialization
completes, set their codetag to empty to avoid warnings when they are
freed later.

This warning is only observed with CONFIG_MEM_ALLOC_PROFILING_DEBUG=Y and
mem_profiling_compressed disabled:

[    9.582133] ------------[ cut here ]------------
[    9.582137] alloc_tag was not set
[    9.582139] WARNING: ./include/linux/alloc_tag.h:164 at __pgalloc_tag_sub+0x40f/0x550, CPU#5: systemd/1
[    9.582190] CPU: 5 UID: 0 PID: 1 Comm: systemd Not tainted 7.0.0-rc4 #1 PREEMPT(lazy)
[    9.582192] Hardware name: Red Hat KVM, BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[    9.582194] RIP: 0010:__pgalloc_tag_sub+0x40f/0x550
[    9.582196] Code: 00 00 4c 29 e5 48 8b 05 1f 88 56 05 48 8d 4c ad 00 48 8d 2c c8 e9 87 fd ff ff 0f 0b 0f 0b e9 f3 fe ff ff 48 8d 3d 61 2f ed 03 <67> 48 0f b9 3a e9 b3 fd ff ff 0f 0b eb e4 e8 5e cd 14 02 4c 89 c7
[    9.582197] RSP: 0018:ffffc9000001f940 EFLAGS: 00010246
[    9.582200] RAX: dffffc0000000000 RBX: 1ffff92000003f2b RCX: 1ffff110200d806c
[    9.582201] RDX: ffff8881006c0360 RSI: 0000000000000004 RDI: ffffffff9bc7b460
[    9.582202] RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff3a62324
[    9.582203] R10: ffffffff9d311923 R11: 0000000000000000 R12: ffffea0004001b00
[    9.582204] R13: 0000000000002000 R14: ffffea0000000000 R15: ffff8881006c0360
[    9.582206] FS:  00007ffbbcf2d940(0000) GS:ffff888450479000(0000) knlGS:0000000000000000
[    9.582208] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    9.582210] CR2: 000055ee3aa260d0 CR3: 0000000148b67005 CR4: 0000000000770ef0
[    9.582211] PKRU: 55555554
[    9.582212] Call Trace:
[    9.582213]  
[    9.582214]  ? __pfx___pgalloc_tag_sub+0x10/0x10
[    9.582216]  ? check_bytes_and_report+0x68/0x140
[    9.582219]  __free_frozen_pages+0x2e4/0x1150
[    9.582221]  ? __free_slab+0xc2/0x2b0
[    9.582224]  qlist_free_all+0x4c/0xf0
[    9.582227]  kasan_quarantine_reduce+0x15d/0x180
[    9.582229]  __kasan_slab_alloc+0x69/0x90
[    9.582232]  kmem_cache_alloc_noprof+0x14a/0x500
[    9.582234]  do_getname+0x96/0x310
[    9.582237]  do_readlinkat+0x91/0x2f0
[    9.582239]  ? __pfx_do_readlinkat+0x10/0x10
[    9.582240]  ? get_random_bytes_user+0x1df/0x2c0
[    9.582244]  __x64_sys_readlinkat+0x96/0x100
[    9.582246]  do_syscall_64+0xce/0x650
[    9.582250]  ? __x64_sys_getrandom+0x13a/0x1e0
[    9.582252]  ? __pfx___x64_sys_getrandom+0x10/0x10
[    9.582254]  ? do_syscall_64+0x114/0x650
[    9.582255]  ? ksys_read+0xfc/0x1d0
[    9.582258]  ? __pfx_ksys_read+0x10/0x10
[    9.582260]  ? do_syscall_64+0x114/0x650
[    9.582262]  ? do_syscall_64+0x114/0x650
[    9.582264]  ? __pfx_fput_close_sync+0x10/0x10
[    9.582266]  ? file_close_fd_locked+0x178/0x2a0
[    9.582268]  ? __x64_sys_faccessat2+0x96/0x100
[    9.582269]  ? __x64_sys_close+0x7d/0xd0
[    9.582271]  ? do_syscall_64+0x114/0x650
[    9.582273]  ? do_syscall_64+0x114/0x650
[    9.582275]  ? clear_bhb_loop+0x50/0xa0
[    9.582277]  ? clear_bhb_loop+0x50/0xa0
[    9.582279]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[    9.582280] RIP: 0033:0x7ffbbda345ee
[    9.582282] Code: 0f 1f 40 00 48 8b 15 29 38 0d 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff c3 0f 1f 40 00 f3 0f 1e fa 49 89 ca b8 0b 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d fa 37 0d 00 f7 d8 64 89 01 48
[    9.582284] RSP: 002b:00007ffe2ad8de58 EFLAGS: 00000202 ORIG_RAX: 000000000000010b
[    9.582286] RAX: ffffffffffffffda RBX: 000055ee3aa25570 RCX: 00007ffbbda345ee
[    9.582287] RDX: 000055ee3aa25570 RSI: 00007ffe2ad8dee0 RDI: 00000000ffffff9c
[    9.582288] RBP: 0000000000001000 R08: 0000000000000003 R09: 0000000000001001
[    9.582289] R10: 0000000000001000 R11: 0000000000000202 R12: 0000000000000033
[    9.582290] R13: 00007ffe2ad8dee0 R14: 00000000ffffff9c R15: 00007ffe2ad8deb0
[    9.582292]  
[    9.582293] ---[ end trace 0000000000000000 ]---

Link: https://lore.kernel.org/20260331081312.123719-1-hao.ge@linux.dev
Fixes: dcfe378c81f72 ("lib: introduce support for page allocation tagging")
Signed-off-by: Hao Ge 
Suggested-by: Suren Baghdasaryan 
Acked-by: Suren Baghdasaryan 
Cc: Kent Overstreet 
Cc: 
Signed-off-by: Andrew Morton

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook

alloc_tag: fix rw permission issue when handling boot parameter

2026-01-31T22:22:37+00:00

Boot parameters prefixed with "sysctl." are processed during the final
stage of system initialization via kernel_init()-> do_sysctl_args().  When
CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled, the sysctl.vm.mem_profiling
entry is not writable and will cause a warning.

Before run_init_process(), system initialization executes in kernel thread
context.  Use current->mm to distinguish sysctl writes during
do_sysctl_args() from user-space triggered ones.

And when the proc_handler is from do_sysctl_args(), always return success
because the same value was already set by setup_early_mem_profiling() and
this eliminates a permission denied warning.

Link: https://lkml.kernel.org/r/20260115031536.164254-1-ranxiaokai627@163.com
Signed-off-by: Ran Xiaokai 
Suggested-by: Suren Baghdasaryan 
Acked-by: Suren Baghdasaryan 
Cc: Kent Overstreet 
Signed-off-by: Andrew Morton

alloc_tag: move memory_allocation_profiling_sysctls into .rodata

2026-01-21T03:24:31+00:00

Remove the change in file mode permissions done before initializing the
sysctl.  It is not necessary as the writing of the kernel variable will be
blocked by the proc_mem_profiling_handler when writing is disallowed (also
controlled by mem_profiling_support).

Link: https://lkml.kernel.org/r/20251215-jag-alloc_tag_const-v1-1-35ea56a1ce13@kernel.org
Signed-off-by: Joel Granados 
Acked-by: Suren Baghdasaryan 
Cc: Kent Overstreet 
Signed-off-by: Andrew Morton

lib/alloc_tag: use %pe format specifier

2025-11-20T21:43:57+00:00

The %pe format specifier is designed to print error pointers.  It prints a
symbolic error name (eg.  -EINVAL) and it makes the code simpler by
omitting PTR_ERR();

This patch fixes this cocci report:
lib/alloc_tag.c:776:63-70: WARNING: Consider using %pe to print PTR_ERR()

Link: https://lkml.kernel.org/r/20251105023925.1447482-1-zeng_chi911@163.com
Signed-off-by: Zeng Chi 
Acked-by: SeongJae Park 
Acked-by: Suren Baghdasaryan 
Cc: Kent Overstreet 
Signed-off-by: Andrew Morton

Merge tag 'mm-nonmm-stable-2025-10-02-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-10-03T01:44:54+00:00

Pull non-MM updates from Andrew Morton:

 - "ida: Remove the ida_simple_xxx() API" from Christophe Jaillet
   completes the removal of this legacy IDR API

 - "panic: introduce panic status function family" from Jinchao Wang
   provides a number of cleanups to the panic code and its various
   helpers, which were rather ad-hoc and scattered all over the place

 - "tools/delaytop: implement real-time keyboard interaction support"
   from Fan Yu adds a few nice user-facing usability changes to the
   delaytop monitoring tool

 - "efi: Fix EFI boot with kexec handover (KHO)" from Evangelos
   Petrongonas fixes a panic which was happening with the combination of
   EFI and KHO

 - "Squashfs: performance improvement and a sanity check" from Phillip
   Lougher teaches squashfs's lseek() about SEEK_DATA/SEEK_HOLE. A mere
   150x speedup was measured for a well-chosen microbenchmark

 - plus another 50-odd singleton patches all over the place

* tag 'mm-nonmm-stable-2025-10-02-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (75 commits)
  Squashfs: reject negative file sizes in squashfs_read_inode()
  kallsyms: use kmalloc_array() instead of kmalloc()
  MAINTAINERS: update Sibi Sankar's email address
  Squashfs: add SEEK_DATA/SEEK_HOLE support
  Squashfs: add additional inode sanity checking
  lib/genalloc: fix device leak in of_gen_pool_get()
  panic: remove CONFIG_PANIC_ON_OOPS_VALUE
  ocfs2: fix double free in user_cluster_connect()
  checkpatch: suppress strscpy warnings for userspace tools
  cramfs: fix incorrect physical page address calculation
  kernel: prevent prctl(PR_SET_PDEATHSIG) from racing with parent process exit
  Squashfs: fix uninit-value in squashfs_get_parent
  kho: only fill kimage if KHO is finalized
  ocfs2: avoid extra calls to strlen() after ocfs2_sprintf_system_inode_name()
  kernel/sys.c: fix the racy usage of task_lock(tsk->group_leader) in sys_prlimit64() paths
  sched/task.h: fix the wrong comment on task_lock() nesting with tasklist_lock
  coccinelle: platform_no_drv_owner: handle also built-in drivers
  coccinelle: of_table: handle SPI device ID tables
  lib/decompress: use designated initializers for struct compress_format
  efi: support booting with kexec handover (KHO)
  ...

alloc_tag: mark inaccurate allocation counters in /proc/allocinfo output

2025-09-21T21:22:36+00:00

While rare, memory allocation profiling can contain inaccurate counters if
slab object extension vector allocation fails.  That allocation might
succeed later but prior to that, slab allocations that would have used
that object extension vector will not be accounted for.  To indicate
incorrect counters, "accurate:no" marker is appended to the call site line
in the /proc/allocinfo output.  Bump up /proc/allocinfo version to reflect
the change in the file format and update documentation.

Example output with invalid counters:
allocinfo - version: 2.0
           0        0 arch/x86/kernel/kdebugfs.c:105 func:create_setup_data_nodes
           0        0 arch/x86/kernel/alternative.c:2090 func:alternatives_smp_module_add
           0        0 arch/x86/kernel/alternative.c:127 func:__its_alloc accurate:no
           0        0 arch/x86/kernel/fpu/regset.c:160 func:xstateregs_set
           0        0 arch/x86/kernel/fpu/xstate.c:1590 func:fpstate_realloc
           0        0 arch/x86/kernel/cpu/aperfmperf.c:379 func:arch_enable_hybrid_capacity_scale
           0        0 arch/x86/kernel/cpu/amd_cache_disable.c:258 func:init_amd_l3_attrs
       49152       48 arch/x86/kernel/cpu/mce/core.c:2709 func:mce_device_create accurate:no
       32768        1 arch/x86/kernel/cpu/mce/genpool.c:132 func:mce_gen_pool_create
           0        0 arch/x86/kernel/cpu/mce/amd.c:1341 func:mce_threshold_create_device

[surenb@google.com: document new "accurate:no" marker]
  Fixes: 39d117e04d15 ("alloc_tag: mark inaccurate allocation counters in /proc/allocinfo output")
[akpm@linux-foundation.org: simplification per Usama, reflow text]
[akpm@linux-foundation.org: add newline to prevent docs warning, per Randy]
Link: https://lkml.kernel.org/r/20250915230224.4115531-1-surenb@google.com
Signed-off-by: Suren Baghdasaryan 
Suggested-by: Johannes Weiner 
Acked-by: Shakeel Butt 
Acked-by: Usama Arif 
Acked-by: Johannes Weiner 
Cc: David Rientjes 
Cc: David Wang <00107082@163.com>
Cc: Kent Overstreet 
Cc: Pasha Tatashin 
Cc: Roman Gushchin 
Cc: Sourav Panda 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

alloc_tag: prevent enabling memory profiling if it was shut down

2025-09-21T21:22:30+00:00

Memory profiling can be shut down due to reasons like a failure during
initialization.  When this happens, the user should not be able to
re-enable it.  Current sysctrl interface does not handle this properly and
will allow re-enabling memory profiling.  Fix this by checking for this
condition during sysctrl write operation.

Link: https://lkml.kernel.org/r/20250915212756.3998938-3-surenb@google.com
Signed-off-by: Suren Baghdasaryan 
Acked-by: Shakeel Butt 
Acked-by: Usama Arif 
Cc: David Wang <00107082@163.com>
Cc: Johannes Weiner 
Cc: Kent Overstreet 
Cc: Pasha Tatashin 
Cc: Sourav Panda 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

alloc_tag: use release_pages() in the cleanup path

2025-09-21T21:22:30+00:00

Patch series "Minor fixes for memory allocation profiling", v2.

Over the last couple months I gathered a few reports of minor issues in
memory allocation profiling which are addressed in this patchset.


This patch (of 2):

When bulk-freeing an array of pages use release_pages() instead of freeing
them page-by-page.

Link: https://lkml.kernel.org/r/20250915212756.3998938-1-surenb@google.com
Link: https://lkml.kernel.org/r/20250915212756.3998938-2-surenb@google.com
Signed-off-by: Suren Baghdasaryan 
Suggested-by: Andrew Morton 
Suggested-by: Usama Arif 
Acked-by: Shakeel Butt 
Acked-by: Usama Arif 
Cc: David Wang <00107082@163.com>
Cc: Johannes Weiner 
Cc: Kent Overstreet 
Cc: Pasha Tatashin 
Cc: Sourav Panda 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

alloc_tag: use str_on_off() helper

2025-09-14T00:32:47+00:00

Replace the ternary (enable ?  "on" : "off") with the str_on_off() helper
from string_choices.h.  This improves readability by replacing the
three-operand ternary with a single function call, ensures consistent
string output, and allows potential string deduplication by the linker,
resulting in a slightly smaller binary.

Link: https://lkml.kernel.org/r/20250814093827.237980-1-visitorckw@gmail.com
Signed-off-by: Kuan-Wei Chiu 
Cc: Ching-Chun (Jim) Huang 
Cc: Kent Overstreet 
Cc: Suren Baghdasaryan 
Signed-off-by: Andrew Morton