FAILED: patch "[PATCH] mm/damon/core: allow esz to be set to zero" failed to apply to 6.1-stable tree

FAILED: patch "[PATCH] mm/damon/core: allow esz to be set to zero" failed to apply to 6.1-stable tree

[gregkh]

The patch below does not apply to the 6.1-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-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 90179da203ba8b708c84a12a07cd44be0f346334
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026092901-ditzy-scarily-fa8f@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

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

From 90179da203ba8b708c84a12a07cd44be0f346334 Mon Sep 17 00:00:00 2001
From: Liew Rui Yan <aethernet65535@gmail.com>
Date: Tue, 8 Sep 2026 06:54:11 -0700
Subject: [PATCH] mm/damon/core: allow esz to be set to zero

When the temporal quota goal tuner determines that the goal has been
achieved (score >= 10000), it sets esz_bp to zero so that the esz becomes
zero.  However, damos_set_effective_quota() clamps the esz to
min_region_sz when quota->ms is set.

This is a minor issue, the main problem is that it doesn't match the
description in the documentation, which state that if the goal has already
been [over-]achieved, the quota will be set to zero.

Fix this by set quota (esz) as minimum as possible.

Link: https://lore.kernel.org/20260908135413.97570-1-sj@kernel.org
Fixes: 8bbde987c2b8 ("mm/damon/core: disallow time-quota setting zero esz")
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Liew Rui Yan <aethernet65535@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: SJ Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # v7.1.x

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 644daf5a1656..2b294fb46648 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -3091,6 +3091,7 @@ static void damos_set_effective_quota(struct damon_ctx *ctx, struct damos *s)
 	struct damos_quota *quota = &s->quota;
 	unsigned long throughput;
 	unsigned long esz = ULONG_MAX;
+	unsigned long esz_time;
 
 	if (!quota->ms && list_empty(&quota->goals)) {
 		quota->esz = quota->sz;
@@ -3111,8 +3112,8 @@ static void damos_set_effective_quota(struct damon_ctx *ctx, struct damos *s)
 					1000000, quota->total_charged_ns);
 		else
 			throughput = PAGE_SIZE * 1024;
-		esz = min(throughput * quota->ms, esz);
-		esz = max(ctx->min_region_sz, esz);
+		esz_time = max(throughput * quota->ms, ctx->min_region_sz);
+		esz = min(esz_time, esz);
 	}
 
 	if (quota->sz && quota->sz < esz)

Re: FAILED: patch "[PATCH] mm/damon/core: allow esz to be set to zero" failed to apply to 6.1-stable tree

[SJ Park]

On Tue, 29 Sep 2026 10:28:01 +0200 <gregkh@linuxfoundation.org> wrote:

> 
> The patch below does not apply to the 6.1-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-6.1.y
> git checkout FETCH_HEAD
> git cherry-pick -x 90179da203ba8b708c84a12a07cd44be0f346334
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026092901-ditzy-scarily-fa8f@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'
> 
> Possible dependencies:
> 
> 
> 
> thanks,
> 
> greg k-h
> 
> ------------------ original commit in Linus's tree ------------------
> 
> >From 90179da203ba8b708c84a12a07cd44be0f346334 Mon Sep 17 00:00:00 2001
> From: Liew Rui Yan <aethernet65535@gmail.com>
> Date: Tue, 8 Sep 2026 06:54:11 -0700
> Subject: [PATCH] mm/damon/core: allow esz to be set to zero
> 
> When the temporal quota goal tuner determines that the goal has been
> achieved (score >= 10000), it sets esz_bp to zero so that the esz becomes
> zero.  However, damos_set_effective_quota() clamps the esz to
> min_region_sz when quota->ms is set.
> 
> This is a minor issue, the main problem is that it doesn't match the
> description in the documentation, which state that if the goal has already
> been [over-]achieved, the quota will be set to zero.
> 
> Fix this by set quota (esz) as minimum as possible.
> 
> Link: https://lore.kernel.org/20260908135413.97570-1-sj@kernel.org
> Fixes: 8bbde987c2b8 ("mm/damon/core: disallow time-quota setting zero esz")

This patch also depends on temporal tuner feature.  It is introduced in 7.1.
Because it is a feature, <7.1 stable kernels don't have the features.  So this
patch shouldn't be applied on 6.6.y.  Please don't port it on 6.6.y.


Thanks,
SJ

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