kernel/linux.git/lib/alloc_tag.c, branch v6.12.107

lib/alloc_tag: introduce mem_alloc_profiling_permanently_disabled()

2026-08-09T18:23:23+00:00

commit a37b0066a10aabf3c968b4566706fb866eaf9a85 upstream. mem_alloc_profiling_enabled() tells whether memalloc profiling is currently enabled. However, even when this function returns false, it can be enabled later. However, this is not enough. Some optimizations can be applied only when memalloc profiling is permanently disabled. For example, to skip the creation of KMALLOC_NO_OBJ_EXT caches at boot time, mem_profiling must be set to "never", "0" w/ debugging on, or have been shutdown so that it can no longer be enabled. Introduce mem_alloc_profiling_permanently_disabled() for this purpose. Signed-off-by: Harry Yoo (Oracle) Acked-by: Suren Baghdasaryan Link: https://patch.msgid.link/20260713-kmalloc-no-objext-v3-3-47c7bd138de7@kernel.org Signed-off-by: Vlastimil Babka (SUSE) [ harry@kernel.org: Move the definition of mem_alloc_profiling_permanently_disabled() after mem_profiling_support. Unlike 6.18 and later kernels, mem_profiling_support is marked __init and gets freed after boot. Since the function is needed only when creating kmalloc caches, mark it __init as well. ] Signed-off-by: Harry Yoo Signed-off-by: Sasha Levin

lib/alloc_tag: do not acquire non-existent lock in alloc_tag_top_users()

2025-07-17T16:37:14+00:00

commit 99af22cd34688cc0d535a1919e0bea4cbc6c1ea1 upstream. alloc_tag_top_users() attempts to lock alloc_tag_cttype->mod_lock even when the alloc_tag_cttype is not allocated because: 1) alloc tagging is disabled because mem profiling is disabled (!alloc_tag_cttype) 2) alloc tagging is enabled, but not yet initialized (!alloc_tag_cttype) 3) alloc tagging is enabled, but failed initialization (!alloc_tag_cttype or IS_ERR(alloc_tag_cttype)) In all cases, alloc_tag_cttype is not allocated, and therefore alloc_tag_top_users() should not attempt to acquire the semaphore. This leads to a crash on memory allocation failure by attempting to acquire a non-existent semaphore: Oops: general protection fault, probably for non-canonical address 0xdffffc000000001b: 0000 [#3] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x00000000000000d8-0x00000000000000df] CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G D 6.16.0-rc2 #1 VOLUNTARY Tainted: [D]=DIE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:down_read_trylock+0xaa/0x3b0 Code: d0 7c 08 84 d2 0f 85 a0 02 00 00 8b 0d df 31 dd 04 85 c9 75 29 48 b8 00 00 00 00 00 fc ff df 48 8d 6b 68 48 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 88 02 00 00 48 3b 5b 68 0f 85 53 01 00 00 65 ff RSP: 0000:ffff8881002ce9b8 EFLAGS: 00010016 RAX: dffffc0000000000 RBX: 0000000000000070 RCX: 0000000000000000 RDX: 000000000000001b RSI: 000000000000000a RDI: 0000000000000070 RBP: 00000000000000d8 R08: 0000000000000001 R09: ffffed107dde49d1 R10: ffff8883eef24e8b R11: ffff8881002cec20 R12: 1ffff11020059d37 R13: 00000000003fff7b R14: ffff8881002cec20 R15: dffffc0000000000 FS: 00007f963f21d940(0000) GS:ffff888458ca6000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f963f5edf71 CR3: 000000010672c000 CR4: 0000000000350ef0 Call Trace: codetag_trylock_module_list+0xd/0x20 alloc_tag_top_users+0x369/0x4b0 __show_mem+0x1cd/0x6e0 warn_alloc+0x2b1/0x390 __alloc_frozen_pages_noprof+0x12b9/0x21a0 alloc_pages_mpol+0x135/0x3e0 alloc_slab_page+0x82/0xe0 new_slab+0x212/0x240 ___slab_alloc+0x82a/0xe00 As David Wang points out, this issue became easier to trigger after commit 780138b12381 ("alloc_tag: check mem_profiling_support in alloc_tag_init"). Before the commit, the issue occurred only when it failed to allocate and initialize alloc_tag_cttype or if a memory allocation fails before alloc_tag_init() is called. After the commit, it can be easily triggered when memory profiling is compiled but disabled at boot. To properly determine whether alloc_tag_init() has been called and its data structures initialized, verify that alloc_tag_cttype is a valid pointer before acquiring the semaphore. If the variable is NULL or an error value, it has not been properly initialized. In such a case, just skip and do not attempt to acquire the semaphore. [harry.yoo@oracle.com: v3] Link: https://lkml.kernel.org/r/20250624072513.84219-1-harry.yoo@oracle.com Link: https://lkml.kernel.org/r/20250620195305.1115151-1-harry.yoo@oracle.com Fixes: 780138b12381 ("alloc_tag: check mem_profiling_support in alloc_tag_init") Fixes: 1438d349d16b ("lib: add memory allocations report in show_mem()") Signed-off-by: Harry Yoo Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202506181351.bba867dd-lkp@intel.com Acked-by: Suren Baghdasaryan Tested-by: Raghavendra K T Cc: Casey Chen Cc: David Wang <00107082@163.com> Cc: Kent Overstreet Cc: Yuanyuan Zhong Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

Merge tag 'sysctl-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl

2024-07-16T21:24:29+00:00

Pull sysctl updates from Joel Granados: - Remove "->procname == NULL" check when iterating through sysctl table arrays Removing sentinels in ctl_table arrays reduces the build time size and runtime memory consumed by ~64 bytes per array. With all ctl_table sentinels gone, the additional check for ->procname == NULL that worked in tandem with the ARRAY_SIZE to calculate the size of the ctl_table arrays is no longer needed and has been removed. The sysctl register functions now returns an error if a sentinel is used. - Preparation patches for sysctl constification Constifying ctl_table structs prevents the modification of proc_handler function pointers as they would reside in .rodata. The ctl_table arguments in sysctl utility functions are const qualified in preparation for a future treewide proc_handler argument constification commit. - Misc fixes Increase robustness of set_ownership by providing sane default ownership values in case the callee doesn't set them. Bound check proc_dou8vec_minmax to avoid loading buggy modules and give sysctl testing module a name to avoid compiler complaints. * tag 'sysctl-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl: sysctl: Warn on an empty procname element sysctl: Remove ctl_table sentinel code comments sysctl: Remove "child" sysctl code comments sysctl: Remove superfluous empty allocations from sysctl internals sysctl: Replace nr_entries with ctl_table_size in new_links sysctl: Remove check for sentinel element in ctl_table arrays mm profiling: Remove superfluous sentinel element from ctl_table locking: Remove superfluous sentinel element from kern_lockdep_table sysctl: Add module description to sysctl-testing sysctl: constify ctl_table arguments of utility function utsname: constify ctl_table arguments of utility function sysctl: move the extra1/2 boundary check of u8 to sysctl_check_table_array sysctl: always initialize i_uid/i_gid

lib/alloc_tag: do not register sysctl interface when CONFIG_SYSCTL=n

2024-06-15T17:43:05+00:00

Memory allocation profiling is trying to register sysctl interface even when CONFIG_SYSCTL=n, resulting in proc_do_static_key() being undefined. Prevent that by skipping sysctl registration for such configurations. Link: https://lkml.kernel.org/r/20240601233831.617124-1-surenb@google.com Fixes: 22d407b164ff ("lib: add allocation tagging support for memory allocation profiling") Signed-off-by: Suren Baghdasaryan Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202405280616.wcOGWJEj-lkp@intel.com/ Acked-by: Vlastimil Babka Cc: Kent Overstreet Cc: Kees Cook Cc: Pasha Tatashin Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton

mm profiling: Remove superfluous sentinel element from ctl_table

2024-06-13T08:50:52+00:00

This commit is part of a greater effort to remove all empty elements at the end of the ctl_table arrays (sentinels) which will reduce the overall build time size of the kernel and run time memory bloat by ~64 bytes per sentinel (further information Link : https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/) Removed sentinel from memory_allocation_profiling_sysctls Signed-off-by: Joel Granados

lib: add version into /proc/allocinfo output

2024-05-24T18:55:05+00:00

Add version string and a header at the beginning of /proc/allocinfo to allow later format changes. Example output: > head /proc/allocinfo allocinfo - version: 1.0 # 0 0 init/main.c:1314 func:do_initcalls 0 0 init/do_mounts.c:353 func:mount_nodev_root 0 0 init/do_mounts.c:187 func:mount_root_generic 0 0 init/do_mounts.c:158 func:do_mount_root 0 0 init/initramfs.c:493 func:unpack_to_rootfs 0 0 init/initramfs.c:492 func:unpack_to_rootfs 0 0 init/initramfs.c:491 func:unpack_to_rootfs 512 1 arch/x86/events/rapl.c:681 func:init_rapl_pmus 128 1 arch/x86/events/rapl.c:571 func:rapl_cpu_online [akpm@linux-foundation.org: remove stray newline from struct allocinfo_private] Link: https://lkml.kernel.org/r/20240514163128.3662251-1-surenb@google.com Signed-off-by: Suren Baghdasaryan Reviewed-by: Pasha Tatashin Reviewed-by: Kees Cook Cc: Kent Overstreet Cc: Vlastimil Babka Signed-off-by: Andrew Morton

alloc_tag: Tighten file permissions on /proc/allocinfo

2024-04-26T03:55:59+00:00

The /proc/allocinfo file exposes a tremendous about of information about kernel build details, memory allocations (obviously), and potentially even image layout (due to ordering). As this is intended to be consumed by system owners (like /proc/slabinfo), use the same file permissions as there: 0400. Link: https://lkml.kernel.org/r/20240425200844.work.184-kees@kernel.org Signed-off-by: Kees Cook Cc: Kent Overstreet Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton

lib: add memory allocations report in show_mem()

2024-04-26T03:55:57+00:00

Include allocations in show_mem reports. Link: https://lkml.kernel.org/r/20240321163705.3067592-33-surenb@google.com Signed-off-by: Kent Overstreet Signed-off-by: Suren Baghdasaryan Reviewed-by: Vlastimil Babka 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: Pasha Tatashin Cc: Peter Zijlstra Cc: Tejun Heo Cc: Wedson Almeida Filho Signed-off-by: Andrew Morton

lib: introduce early boot parameter to avoid page_ext memory overhead

2024-04-26T03:55:53+00:00

The highest memory overhead from memory allocation profiling comes from page_ext objects. This overhead exists even if the feature is disabled but compiled-in. To avoid it, introduce an early boot parameter that prevents page_ext object creation. The new boot parameter is a tri-state with possible values of 0|1|never. When it is set to "never" the memory allocation profiling support is disabled, and overhead is minimized (currently no page_ext objects are allocated, in the future more overhead might be eliminated). As a result we also lose ability to enable memory allocation profiling at runtime (because there is no space to store alloctag references). Runtime sysctrl becomes read-only if the early boot parameter was set to "never". Note that the default value of this boot parameter depends on the CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT configuration. When CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=n the boot parameter is set to "never", therefore eliminating any overhead. CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=y results in boot parameter being set to 1 (enabled). This allows distributions to avoid any overhead by setting CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=n config and with no changes to the kernel command line. We reuse sysctl.vm.mem_profiling boot parameter name in order to avoid introducing yet another control. This change turns it into a tri-state early boot parameter. Link: https://lkml.kernel.org/r/20240321163705.3067592-16-surenb@google.com Signed-off-by: Suren Baghdasaryan Reviewed-by: Vlastimil Babka 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: Kent Overstreet Cc: Miguel Ojeda Cc: Pasha Tatashin Cc: Peter Zijlstra Cc: Tejun Heo Cc: Wedson Almeida Filho Signed-off-by: Andrew Morton

lib: introduce support for page allocation tagging

2024-04-26T03:55:53+00:00

Introduce helper functions to easily instrument page allocators by storing a pointer to the allocation tag associated with the code that allocated the page in a page_ext field. Link: https://lkml.kernel.org/r/20240321163705.3067592-15-surenb@google.com Signed-off-by: Suren Baghdasaryan Co-developed-by: Kent Overstreet Signed-off-by: Kent Overstreet Reviewed-by: Vlastimil Babka 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: Pasha Tatashin Cc: Peter Zijlstra Cc: Tejun Heo Cc: Wedson Almeida Filho Signed-off-by: Andrew Morton