The patch titled Subject: alloc_tag: avoid current->alloc_tag manipulations when profiling is disabled has been added to the -mm mm-hotfixes-unstable branch. Its filename is alloc_tag-avoid-current-alloc_tag-manipulations-when-profiling-is-disabled.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Suren Baghdasaryan surenb@google.com Subject: alloc_tag: avoid current->alloc_tag manipulations when profiling is disabled Date: Thu, 26 Dec 2024 13:16:38 -0800

When memory allocation profiling is disabled there is no need to update current->alloc_tag and these manipulations add unnecessary overhead. Fix the overhead by skipping these extra updates.

Link: https://lkml.kernel.org/r/20241226211639.1357704-1-surenb@google.com Fixes: b951aaff5035 ("mm: enable page allocation tagging") Signed-off-by: Suren Baghdasaryan surenb@google.com Cc: David Wang 00107082@163.com Cc: Kent Overstreet kent.overstreet@linux.dev Cc: Yu Zhao yuzhao@google.com Cc: Zhenhua Huang quic_zhenhuah@quicinc.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

include/linux/alloc_tag.h | 11 ++++++++--- lib/alloc_tag.c | 2 ++ 2 files changed, 10 insertions(+), 3 deletions(-)

--- a/include/linux/alloc_tag.h~alloc_tag-avoid-current-alloc_tag-manipulations-when-profiling-is-disabled +++ a/include/linux/alloc_tag.h @@ -224,9 +224,14 @@ static inline void alloc_tag_sub(union c

#define alloc_hooks_tag(_tag, _do_alloc) \ ({ \ - struct alloc_tag * __maybe_unused _old = alloc_tag_save(_tag); \ - typeof(_do_alloc) _res = _do_alloc; \ - alloc_tag_restore(_tag, _old); \ + typeof(_do_alloc) _res; \ + if (mem_alloc_profiling_enabled()) { \ + struct alloc_tag * __maybe_unused _old; \ + _old = alloc_tag_save(_tag); \ + _res = _do_alloc; \ + alloc_tag_restore(_tag, _old); \ + } else \ + _res = _do_alloc; \ _res; \ })

--- a/lib/alloc_tag.c~alloc_tag-avoid-current-alloc_tag-manipulations-when-profiling-is-disabled +++ a/lib/alloc_tag.c @@ -29,6 +29,8 @@ EXPORT_SYMBOL(_shared_alloc_tag);

DEFINE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT, mem_alloc_profiling_key); +EXPORT_SYMBOL(mem_alloc_profiling_key); + DEFINE_STATIC_KEY_FALSE(mem_profiling_compressed);

struct alloc_tag_kernel_section kernel_tags = { NULL, 0 }; _

Patches currently in -mm which might be from surenb@google.com are

alloc_tag-avoid-current-alloc_tag-manipulations-when-profiling-is-disabled.patch alloc_tag-skip-pgalloc_tag_swap-if-profiling-is-disabled.patch seqlock-add-raw_seqcount_try_begin.patch mm-convert-mm_lock_seq-to-a-proper-seqcount.patch mm-introduce-mmap_lock_speculate_try_beginretry.patch mm-introduce-vma_start_read_locked_nested-helpers.patch mm-move-per-vma-lock-into-vm_area_struct.patch mm-mark-vma-as-detached-until-its-added-into-vma-tree.patch mm-modify-vma_iter_store_gfp-to-indicate-if-its-storing-a-new-vma.patch mm-mark-vmas-detached-upon-exit.patch mm-nommu-fix-the-last-places-where-vma-is-not-locked-before-being-attached.patch types-move-struct-rcuwait-into-typesh.patch mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch mm-move-mmap_init_lock-out-of-the-header-file.patch mm-uninline-the-main-body-of-vma_start_write.patch refcount-introduce-__refcount_addinc_not_zero_limited.patch mm-replace-vm_lock-and-detached-flag-with-a-reference-count.patch mm-debug-print-vm_refcnt-state-when-dumping-the-vma.patch mm-debug-print-vm_refcnt-state-when-dumping-the-vma-fix.patch mm-remove-extra-vma_numab_state_init-call.patch mm-prepare-lock_vma_under_rcu-for-vma-reuse-possibility.patch mm-make-vma-cache-slab_typesafe_by_rcu.patch docs-mm-document-latest-changes-to-vm_lock.patch