FAILED: patch "[PATCH] alloc_tag: skip pgalloc_tag_swap if profiling is disabled" failed to apply to 6.12-stable tree

FAILED: patch "[PATCH] alloc_tag: skip pgalloc_tag_swap if profiling is disabled" failed to apply to 6.12-stable tree

[gregkh]

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 05c82ee363f64c64b87a0cfd744298e9333475f5
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025012056-marina-lagging-26cc@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 05c82ee363f64c64b87a0cfd744298e9333475f5 Mon Sep 17 00:00:00 2001
From: Suren Baghdasaryan <surenb@google.com>
Date: Thu, 26 Dec 2024 13:16:39 -0800
Subject: [PATCH] alloc_tag: skip pgalloc_tag_swap if profiling is disabled

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

Once I added these checks, the overhead of the mode when memory profiling
is enabled but turned off went down by about 50%.

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>

diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
index 7dcebf118a3e..65e706e1bc19 100644
--- a/lib/alloc_tag.c
+++ b/lib/alloc_tag.c
@@ -195,6 +195,9 @@ void pgalloc_tag_swap(struct folio *new, struct folio *old)
 	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;