FAILED: patch "[PATCH] sched/cache: Skip kernel threads for cache aware scheduling" failed to apply to 7.2-stable tree
Subsystems (2)
[email protected]
maintainerThe patch below does not apply to the 7.2-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 <[email protected]>.
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-7.2.y
git checkout FETCH_HEAD
git cherry-pick -x 65efcccddc83d6a19e8a2e2a6117811e39e589bf
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026092935-angelic-kick-1d0a@gregkh' --subject-prefix 'PATCH 7.2.y' 'HEAD^..'
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 65efcccddc83d6a19e8a2e2a6117811e39e589bf Mon Sep 17 00:00:00 2001
From: Chen Yu <[email protected]>
Date: Mon, 21 Sep 2026 17:37:26 -0700
Subject: [PATCH] sched/cache: Skip kernel threads for cache aware scheduling
to rubustify the code
Kernel thread should not be covered by cache aware scheduling as it borrows the statistics from the user space thread. Filter the kernel thread in account_mm_sched().
In theory a kernel thread does not have any valid cache group, so !grp should gate the kernel thread. Add the PF_KTHREAD check explicitly here for safety reasons, to guard against future modifications and to pair with task_tick_cache().
kernel/sched/fair.c +7 -1
@@ -1907,8 +1907,14 @@ void account_mm_sched(struct rq *rq, struct task_struct *p, s64 delta_exec)/* * init_task, kthreads and user thread created * by user_mode_thread() don't have a cache group. +* In theory a kernel thread does not have any valid +* cache group, because sched_cache_fork() is not +* invoked for a kernel thread - !grp should gate the +* kernel thread. Use the PF_KTHREAD check explicitly +* here for safety reasons, to guard against future +* modifications and to pair with task_tick_cache(). */ -if (!grp || !grp->pcpu_sched) +if (p->flags &PF_KTHREAD || !grp || !grp->pcpu_sched)return ; pcpu_sched =per_cpu_ptr (grp->pcpu_sched,cpu_of (rq));
Quoted 7 lines · On Tue, 2026-09-29 at 13:43 +0200, [email protected] wrote:
The patch below does not apply to the 7.2-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 <[email protected]>.To reproduce the conflict and resubmit, you may use the following commands:
Quoted 9 lines
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-7.2.y
git checkoutFETCH_HEAD
git cherry-pick -x65efcccddc83d6a19e8a2e2a6117811e39e589bf
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026092935-angelic-kick-1d0a@gregkh' --subject-prefix 'PATCH 7.2.y' 'HEAD^..'Possible dependencies:
These patches in upstream needs to be applied first before this patch:f0d243a96f268 sched/fair: Avoid creating misfits during cache-aware balancing (should be included in stable) 28f9c0e0a0b94 sched/cache: Decouple sched_cache_group from mm to fix UAF (just merged in stable) b636fef85bda7 sched/cache: Introduce task_struct->sched_cache_grp to fix UAF (should be included in stable)
Thanks.
Tim
Quoted 52 lines
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From
65efcccddc83d6a19e8a2e2a6117811e39e589bfMon Sep 17 00:00:00 2001
From: Chen Yu <[email protected]>
Date: Mon, 21 Sep 2026 17:37:26 -0700
Subject: [PATCH] sched/cache: Skip kernel threads for cache aware scheduling
to rubustify the codeKernel thread should not be covered by cache aware scheduling as it borrows the statistics from the user space thread. Filter the kernel thread in
account_mm_sched().In theory a kernel thread does not have any valid cache group, so !grp should gate the kernel thread. Add the
PF_KTHREADcheck explicitly here for safety reasons, to guard against future modifications and to pair withtask_tick_cache().Fixes df0d98475954 ("sched/cache: Introduce infrastructure for cache-aware load balancing")Signed-off-by Chen Yu <[email protected]>Signed-off-by Tim Chen <[email protected]>Signed-off-by Peter Zijlstra (Intel) <[email protected]>Signed-off-by Ingo Molnar <[email protected]>Cc <[email protected]> # 7.2.xkernel/sched/fair.c +7
-1@@ -1907,8 +1907,14 @@ void account_mm_sched(struct rq *rq, struct task_struct *p, s64 delta_exec)/* * init_task, kthreads and user thread created * by user_mode_thread() don't have a cache group. +* In theory a kernel thread does not have any valid +* cache group, because sched_cache_fork() is not +* invoked for a kernel thread - !grp should gate the +* kernel thread. Use the PF_KTHREAD check explicitly +* here for safety reasons, to guard against future +* modifications and to pair with task_tick_cache(). */ -if (!grp || !grp->pcpu_sched) +if (p->flags &PF_KTHREAD || !grp || !grp->pcpu_sched)return ; pcpu_sched =per_cpu_ptr (grp->pcpu_sched,cpu_of (rq));
Greg KH
maintainerQuoted 15 lines · Tim Chen
Quoted 14 lines · On Tue, 2026-09-29 at 13:43 +0200, [email protected] wrote:
The patch below does not apply to the 7.2-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 <[email protected]>.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-7.2.y
git checkoutFETCH_HEAD
git cherry-pick -x65efcccddc83d6a19e8a2e2a6117811e39e589bf
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026092935-angelic-kick-1d0a@gregkh' --subject-prefix 'PATCH 7.2.y' 'HEAD^..'
Quoted 7 lines
Quoted 2 lines
Possible dependencies:
These patches in upstream needs to be applied first before this patch:
f0d243a96f268sched/fair: Avoid creating misfits during cache-aware balancing (should be included in stable)28f9c0e0a0b94sched/cache: Decouplesched_cache_groupfrom mm to fix UAF (just merged in stable)b636fef85bda7sched/cache: Introducetask_struct->sched_cache_grpto fix UAF (should be included in stable)
Can you send a proper series?
thanks,
greg k-h
Quoted 19 lines · Greg KH
Quoted 18 lines · Tim Chen
Quoted 16 lines · On Tue, 2026-09-29 at 13:43 +0200, [email protected] wrote:
The patch below does not apply to the 7.2-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 <[email protected]>.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-7.2.y
git checkoutFETCH_HEAD
git cherry-pick -x65efcccddc83d6a19e8a2e2a6117811e39e589bf
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026092935-angelic-kick-1d0a@gregkh' --subject-prefix 'PATCH 7.2.y' 'HEAD^..'Possible dependencies:
Quoted 6 lines
Quoted 4 lines
These patches in upstream needs to be applied first before this patch:
f0d243a96f268sched/fair: Avoid creating misfits during cache-aware balancing (should be included in stable)28f9c0e0a0b94sched/cache: Decouplesched_cache_groupfrom mm to fix UAF (just merged in stable)b636fef85bda7sched/cache: Introducetask_struct->sched_cache_grpto fix UAF (should be included in stable)Can you send a proper series?
Hi Greg,
Sorry for the troubles. I have sent you a series that included all the patches. Some you may have already applied but I still included them so show the order of the patches.
Thanks.
Tim
Quoted 4 lines
thanks,
greg k-h