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FAILED: patch "[PATCH] mm: take into account mm_cid size for mm_struct static" failed to apply to 6.18-stable tree

PATCH [email protected] 1 participant 1 message Jan 26

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The patch below does not apply to the 6.18-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-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x be31340a4cc259340044b7fc4f7e97f58c74ee8e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026012616-countable-embargo-bbcb@gregkh' --subject-prefix 'PATCH 6.18.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From be31340a4cc259340044b7fc4f7e97f58c74ee8e Mon Sep 17 00:00:00 2001
From: Mathieu Desnoyers <[email protected]>
Date: Wed, 24 Dec 2025 12:33:58 -0500
Subject: [PATCH] mm: take into account mm_cid size for mm_struct static
definitions
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Both init_mm and efi_mm static definitions need to make room for the 2 mm_cid cpumasks.

This fixes possible out-of-bounds accesses to init_mm and efi_mm.

Add a space between # and define for the mm_alloc_cid() definition to make it consistent with the coding style used in the rest of this header file.

Link https://lkml.kernel.org/r/[email protected] open here
Fixes af7f588d8f73 ("sched: Introduce per-memory-map concurrency ID")
Signed-off-by Mathieu Desnoyers <[email protected]>
Reviewed-by Thomas Gleixner <[email protected]>
Cc Mark Brown <[email protected]>
Cc Aboorva Devarajan <[email protected]>
Cc Al Viro <[email protected]>
Cc Baolin Wang <[email protected]>
Cc Christan König <[email protected]>
Cc Christian Brauner <[email protected]>
Cc Christoph Lameter <[email protected]>
Cc David Hildenbrand <[email protected]>
Cc David Rientjes <[email protected]>
Cc Dennis Zhou <[email protected]>
Cc Johannes Weiner <[email protected]>
Cc "Liam R . Howlett" <[email protected]>
Cc Lorenzo Stoakes <[email protected]>
Cc Martin Liu <[email protected]>
Cc Masami Hiramatsu <[email protected]>
Cc Mateusz Guzik <[email protected]>
Cc Matthew Wilcox <[email protected]>
Cc Miaohe Lin <[email protected]>
Cc Michal Hocko <[email protected]>
Cc Mike Rapoport <[email protected]>
Cc "Paul E. McKenney" <[email protected]>
Cc Roman Gushchin <[email protected]>
Cc SeongJae Park <[email protected]>
Cc Shakeel Butt <[email protected]>
Cc Steven Rostedt <[email protected]>
Cc Suren Baghdasaryan <[email protected]>
Cc Sweet Tea Dorminy <[email protected]>
Cc Tejun Heo <[email protected]>
Cc Vlastimil Babka <[email protected]>
Cc Wei Yang <[email protected]>
Cc Yu Zhao <[email protected]>
Cc Peter Zijlstra (Intel) <[email protected]>
Cc <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
include/linux/mm_types.h +5 -2
index 110b319a2ffb..aa4639888f89 100644
@@ -1368,7 +1368,7 @@ extern struct mm_struct init_mm;
 
 #define MM_STRUCT_FLEXIBLE_ARRAY_INIT				\
 {								\
-	[0 ... sizeof(cpumask_t)-1] = 0				\
+	[0 ... sizeof(cpumask_t) + MM_CID_STATIC_SIZE - 1] = 0	\
 }
 
 /* Pointer magic because the dynamic array size confuses some compilers. */

@@ -1500,7 +1500,7 @@ static inline int mm_alloc_cid_noprof(struct mm_struct *mm, struct task_struct *
 	mm_init_cid(mm, p);
 	return 0;
 }
-#define mm_alloc_cid(...)	alloc_hooks(mm_alloc_cid_noprof(__VA_ARGS__))
+# define mm_alloc_cid(...)	alloc_hooks(mm_alloc_cid_noprof(__VA_ARGS__))
 
 static inline void mm_destroy_cid(struct mm_struct *mm)
 {

@@ -1514,6 +1514,8 @@ static inline unsigned int mm_cid_size(void)
 	return cpumask_size() + bitmap_size(num_possible_cpus());
 }
 
+/* Use 2 * NR_CPUS as worse case for static allocation. */
+# define MM_CID_STATIC_SIZE	(2 * sizeof(cpumask_t))
 #else /* CONFIG_SCHED_MM_CID */
 static inline void mm_init_cid(struct mm_struct *mm, struct task_struct *p) { }
 static inline int mm_alloc_cid(struct mm_struct *mm, struct task_struct *p) { return 0; }

@@ -1522,6 +1524,7 @@ static inline unsigned int mm_cid_size(void)
 {
 	return 0;
 }
+# define MM_CID_STATIC_SIZE	0
 #endif /* CONFIG_SCHED_MM_CID */
 
 struct mmu_gather;