--- /dev/null
+From b94d45b6bbb42571ec225d3be0e7457c8765a5b4 Mon Sep 17 00:00:00 2001
+From: Peter Zijlstra <peterz@infradead.org>
+Date: Tue, 28 Oct 2025 09:56:38 +0100
+Subject: seqlock: Allow KASAN to fail optimizing
+
+From: Peter Zijlstra <peterz@infradead.org>
+
+commit b94d45b6bbb42571ec225d3be0e7457c8765a5b4 upstream.
+
+Some KASAN builds are failing to properly optimize this code --
+luckily we don't care about core quality for KASAN builds, so just
+exclude it.
+
+Reported-by: kernel test robot <lkp@intel.com>
+Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
+Closes: https://lore.kernel.org/oe-kbuild-all/202510251641.idrNXhv5-lkp@intel.com/
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ include/linux/seqlock.h | 5 ++++-
+ 1 file changed, 4 insertions(+), 1 deletion(-)
+
+--- a/include/linux/seqlock.h
++++ b/include/linux/seqlock.h
+@@ -1234,11 +1234,14 @@ static __always_inline void __scoped_seq
+
+ extern void __scoped_seqlock_invalid_target(void);
+
+-#if defined(CONFIG_CC_IS_GCC) && CONFIG_GCC_VERSION < 90000
++#if (defined(CONFIG_CC_IS_GCC) && CONFIG_GCC_VERSION < 90000) || defined(CONFIG_KASAN)
+ /*
+ * For some reason some GCC-8 architectures (nios2, alpha) have trouble
+ * determining that the ss_done state is impossible in __scoped_seqlock_next()
+ * below.
++ *
++ * Similarly KASAN is known to confuse compilers enough to break this. But we
++ * don't care about code quality for KASAN builds anyway.
+ */
+ static inline void __scoped_seqlock_bug(void) { }
+ #else
--- /dev/null
+From 88331c4ec23a28c1006ec532fa64763d4c695e90 Mon Sep 17 00:00:00 2001
+From: Heiko Carstens <hca@linux.ibm.com>
+Date: Tue, 19 May 2026 13:03:15 +0200
+Subject: seqlock: Allow UBSAN_ALIGNMENT to fail optimizing
+
+From: Heiko Carstens <hca@linux.ibm.com>
+
+commit 88331c4ec23a28c1006ec532fa64763d4c695e90 upstream.
+
+With gcc-15 and gcc-16 with UBSAN_ALIGNMENT enabled the compiler fails to
+inline and optimize __scoped_seqlock_bug() away on s390:
+
+s390x-16.1.0-ld: kernel/sched/build_policy.o: in function `__scoped_seqlock_next':
+/.../seqlock.h:1286:(.text+0x22030): undefined reference to `__scoped_seqlock_bug'
+
+Fix this by adding UBSAN_ALIGNMENT to the list of config options where a
+not inlined empty __scoped_seqlock_bug() is allowed.
+
+Closes: https://lore.kernel.org/r/20260515092057.810542-1-arnd@kernel.org/
+Reported-by: Arnd Bergmann <arnd@arndb.de>
+Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
+Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
+Link: https://patch.msgid.link/20260519110315.1385307-1-hca@linux.ibm.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ include/linux/seqlock.h | 7 ++++---
+ 1 file changed, 4 insertions(+), 3 deletions(-)
+
+--- a/include/linux/seqlock.h
++++ b/include/linux/seqlock.h
+@@ -1234,14 +1234,15 @@ static __always_inline void __scoped_seq
+
+ extern void __scoped_seqlock_invalid_target(void);
+
+-#if (defined(CONFIG_CC_IS_GCC) && CONFIG_GCC_VERSION < 90000) || defined(CONFIG_KASAN)
++#if (defined(CONFIG_CC_IS_GCC) && CONFIG_GCC_VERSION < 90000) || \
++ defined(CONFIG_KASAN) || defined(CONFIG_UBSAN_ALIGNMENT)
+ /*
+ * For some reason some GCC-8 architectures (nios2, alpha) have trouble
+ * determining that the ss_done state is impossible in __scoped_seqlock_next()
+ * below.
+ *
+- * Similarly KASAN is known to confuse compilers enough to break this. But we
+- * don't care about code quality for KASAN builds anyway.
++ * Similarly KASAN and UBSAN_ALIGNMENT are known to confuse compilers enough
++ * to break this. But we don't care about code quality for such builds anyway.
+ */
+ static inline void __scoped_seqlock_bug(void) { }
+ #else
--- /dev/null
+From 90dfeef1cd38dff19f8b3a752d13bfd79f0f7694 Mon Sep 17 00:00:00 2001
+From: Peter Zijlstra <peterz@infradead.org>
+Date: Thu, 4 Dec 2025 11:43:32 +0100
+Subject: seqlock: Cure some more scoped_seqlock() optimization fails
+
+From: Peter Zijlstra <peterz@infradead.org>
+
+commit 90dfeef1cd38dff19f8b3a752d13bfd79f0f7694 upstream.
+
+Arnd reported an x86 randconfig using gcc-15 tripped over
+__scoped_seqlock_bug(). Turns out GCC chose not to inline the
+scoped_seqlock helper functions and as such was not able to optimize
+properly.
+
+[ mingo: Clang fails the build too in some circumstances. ]
+
+Reported-by: Arnd Bergmann <arnd@arndb.de>
+Tested-by: Arnd Bergmann <arnd@arndb.de>
+Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
+Signed-off-by: Ingo Molnar <mingo@kernel.org>
+Cc: Oleg Nesterov <oleg@redhat.com>
+Link: https://patch.msgid.link/20251204104332.GG2528459@noisy.programming.kicks-ass.net
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ include/linux/seqlock.h | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/include/linux/seqlock.h
++++ b/include/linux/seqlock.h
+@@ -1224,7 +1224,7 @@ struct ss_tmp {
+ spinlock_t *lock_irqsave;
+ };
+
+-static inline void __scoped_seqlock_cleanup(struct ss_tmp *sst)
++static __always_inline void __scoped_seqlock_cleanup(struct ss_tmp *sst)
+ {
+ if (sst->lock)
+ spin_unlock(sst->lock);
+@@ -1249,7 +1249,7 @@ static inline void __scoped_seqlock_bug(
+ extern void __scoped_seqlock_bug(void);
+ #endif
+
+-static inline void
++static __always_inline void
+ __scoped_seqlock_next(struct ss_tmp *sst, seqlock_t *lock, enum ss_state target)
+ {
+ switch (sst->state) {
netfilter-nf_tables-revert-commit_mutex-usage-in-res.patch
drm-virtio-fix-deadlock-in-display_info_cb-by-removi.patch
fs-proc-task_mmu-fix-make_uffd_wp_huge_pte-prot-upda.patch
+seqlock-cure-some-more-scoped_seqlock-optimization-fails.patch
+seqlock-allow-kasan-to-fail-optimizing.patch
+seqlock-allow-ubsan_alignment-to-fail-optimizing.patch
projects / thirdparty / kernel / stable-queue.git / commitdiff
