+ ipc-only-destroy-orphaned-shm-segments-on-sysctl-write.patch added to mm-nonmm-unstable branch

+ ipc-only-destroy-orphaned-shm-segments-on-sysctl-write.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: ipc: only destroy orphaned shm segments on sysctl write
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     ipc-only-destroy-orphaned-shm-segments-on-sysctl-write.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/ipc-only-destroy-orphaned-shm-segments-on-sysctl-write.patch

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

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------------------------------------------------------
From: Jianlin Shi <shijianlin11@foxmail.com>
Subject: ipc: only destroy orphaned shm segments on sysctl write
Date: Mon, 15 Jun 2026 10:27:41 +0800

proc_ipc_dointvec_minmax_orphans() currently calls shm_destroy_orphaned()
whenever shm_rmid_forced is set, including on sysctl reads.  Reading
/proc/sys/kernel/shm_rmid_forced should not take shm_ids rwsem for write
and walk all segments.

Only run the cleanup when the sysctl is written and the forced RMID policy
is enabled.

When shm_rmid_forced=1, monitoring tools that read
/proc/sys/kernel/shm_rmid_forced trigger the cleanup on every read.

Link: https://lore.kernel.org/all/?q=only+destroy+orphaned+shm+segments+on+sysctl+write
Link: https://lore.kernel.org/tencent_738A8BC6E9EA205F555E4B0DAA154D4F8E0A@qq.com
Signed-off-by: Jianlin Shi <shijianlin11@foxmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 ipc/ipc_sysctl.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/ipc/ipc_sysctl.c~ipc-only-destroy-orphaned-shm-segments-on-sysctl-write
+++ a/ipc/ipc_sysctl.c
@@ -28,7 +28,7 @@ static int proc_ipc_dointvec_minmax_orph
 
 	if (err < 0)
 		return err;
-	if (ns->shm_rmid_forced)
+	if (write && ns->shm_rmid_forced)
 		shm_destroy_orphaned(ns);
 	return err;
 }
_

Patches currently in -mm which might be from shijianlin11@foxmail.com are

ipc-only-destroy-orphaned-shm-segments-on-sysctl-write.patch