+ alloc_tag-skip-pgalloc_tag_swap-if-profiling-is-disabled.patch added to mm-hotfixes-unstable branch

+ alloc_tag-skip-pgalloc_tag_swap-if-profiling-is-disabled.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: alloc_tag: skip pgalloc_tag_swap if profiling is disabled
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     alloc_tag-skip-pgalloc_tag_swap-if-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/alloc_tag-skip-pgalloc_tag_swap-if-profiling-is-disabled.patch

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

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Suren Baghdasaryan <surenb@google.com>
Subject: alloc_tag: skip pgalloc_tag_swap if profiling is disabled
Date: Thu, 26 Dec 2024 13:16:39 -0800

When memory allocation profiling is disabled, there is no need to swap
allocation tags during migration.  Skip it to avoid unnecessary overhead.

Link: https://lkml.kernel.org/r/20241226211639.1357704-2-surenb@google.com
Fixes: e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()")
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>
---

 lib/alloc_tag.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/lib/alloc_tag.c~alloc_tag-skip-pgalloc_tag_swap-if-profiling-is-disabled
+++ a/lib/alloc_tag.c
@@ -197,6 +197,9 @@ void pgalloc_tag_swap(struct folio *new,
 	union codetag_ref ref_old, ref_new;
 	struct alloc_tag *tag_old, *tag_new;
 
+	if (!mem_alloc_profiling_enabled())
+		return;
+
 	tag_old = pgalloc_tag_get(&old->page);
 	if (!tag_old)
 		return;
_

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