6.6-stable review patch. If anyone has any objections, please let me know.
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From: Masahiro Yamada masahiroy@kernel.org
[ Upstream commit dbefa1f31a91670c9e7dac9b559625336206466f ]
Commit b1fca27d384e ("kernel debug: support resetting WARN*_ONCE") added support for clearing the state of once warnings. However, it is not functional when CONFIG_LD_DEAD_CODE_DATA_ELIMINATION or CONFIG_LTO_CLANG is enabled, because .data.once matches the .data.[0-9a-zA-Z_]* pattern in the DATA_MAIN macro.
Commit cb87481ee89d ("kbuild: linker script do not match C names unless LD_DEAD_CODE_DATA_ELIMINATION is configured") was introduced to suppress the issue for the default CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=n case, providing a minimal fix for stable backporting. We were aware this did not address the issue for CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y. The plan was to apply correct fixes and then revert cb87481ee89d. [1]
Seven years have passed since then, yet the #ifdef workaround remains in place. Meanwhile, commit b1fca27d384e introduced the .data.once section, and commit dc5723b02e52 ("kbuild: add support for Clang LTO") extended the #ifdef.
Using a ".." separator in the section name fixes the issue for CONFIG_LD_DEAD_CODE_DATA_ELIMINATION and CONFIG_LTO_CLANG.
[1]: https://lore.kernel.org/linux-kbuild/CAK7LNASck6BfdLnESxXUeECYL26yUDm0cwRZuM...
Fixes: b1fca27d384e ("kernel debug: support resetting WARN*_ONCE") Fixes: dc5723b02e52 ("kbuild: add support for Clang LTO") Signed-off-by: Masahiro Yamada masahiroy@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/asm-generic/vmlinux.lds.h | 2 +- include/linux/mmdebug.h | 6 +++--- include/linux/once.h | 4 ++-- include/linux/once_lite.h | 2 +- include/net/net_debug.h | 2 +- mm/internal.h | 2 +- 6 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index cb12f164caf1e..7e11ca6f86dcd 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -349,7 +349,7 @@ *(.data..shared_aligned) /* percpu related */ \ *(.data..unlikely) \ __start_once = .; \ - *(.data.once) \ + *(.data..once) \ __end_once = .; \ STRUCT_ALIGN(); \ *(__tracepoints) \ diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h index 7c3e7b0b0e8fd..28c21d5b25f6b 100644 --- a/include/linux/mmdebug.h +++ b/include/linux/mmdebug.h @@ -46,7 +46,7 @@ void vma_iter_dump_tree(const struct vma_iterator *vmi); } \ } while (0) #define VM_WARN_ON_ONCE_PAGE(cond, page) ({ \ - static bool __section(".data.once") __warned; \ + static bool __section(".data..once") __warned; \ int __ret_warn_once = !!(cond); \ \ if (unlikely(__ret_warn_once && !__warned)) { \ @@ -66,7 +66,7 @@ void vma_iter_dump_tree(const struct vma_iterator *vmi); unlikely(__ret_warn); \ }) #define VM_WARN_ON_ONCE_FOLIO(cond, folio) ({ \ - static bool __section(".data.once") __warned; \ + static bool __section(".data..once") __warned; \ int __ret_warn_once = !!(cond); \ \ if (unlikely(__ret_warn_once && !__warned)) { \ @@ -77,7 +77,7 @@ void vma_iter_dump_tree(const struct vma_iterator *vmi); unlikely(__ret_warn_once); \ }) #define VM_WARN_ON_ONCE_MM(cond, mm) ({ \ - static bool __section(".data.once") __warned; \ + static bool __section(".data..once") __warned; \ int __ret_warn_once = !!(cond); \ \ if (unlikely(__ret_warn_once && !__warned)) { \ diff --git a/include/linux/once.h b/include/linux/once.h index bc714d414448a..30346fcdc7995 100644 --- a/include/linux/once.h +++ b/include/linux/once.h @@ -46,7 +46,7 @@ void __do_once_sleepable_done(bool *done, struct static_key_true *once_key, #define DO_ONCE(func, ...) \ ({ \ bool ___ret = false; \ - static bool __section(".data.once") ___done = false; \ + static bool __section(".data..once") ___done = false; \ static DEFINE_STATIC_KEY_TRUE(___once_key); \ if (static_branch_unlikely(&___once_key)) { \ unsigned long ___flags; \ @@ -64,7 +64,7 @@ void __do_once_sleepable_done(bool *done, struct static_key_true *once_key, #define DO_ONCE_SLEEPABLE(func, ...) \ ({ \ bool ___ret = false; \ - static bool __section(".data.once") ___done = false; \ + static bool __section(".data..once") ___done = false; \ static DEFINE_STATIC_KEY_TRUE(___once_key); \ if (static_branch_unlikely(&___once_key)) { \ ___ret = __do_once_sleepable_start(&___done); \ diff --git a/include/linux/once_lite.h b/include/linux/once_lite.h index b7bce4983638f..27de7bc32a061 100644 --- a/include/linux/once_lite.h +++ b/include/linux/once_lite.h @@ -12,7 +12,7 @@
#define __ONCE_LITE_IF(condition) \ ({ \ - static bool __section(".data.once") __already_done; \ + static bool __section(".data..once") __already_done; \ bool __ret_cond = !!(condition); \ bool __ret_once = false; \ \ diff --git a/include/net/net_debug.h b/include/net/net_debug.h index 1e74684cbbdbc..4a79204c8d306 100644 --- a/include/net/net_debug.h +++ b/include/net/net_debug.h @@ -27,7 +27,7 @@ void netdev_info(const struct net_device *dev, const char *format, ...);
#define netdev_level_once(level, dev, fmt, ...) \ do { \ - static bool __section(".data.once") __print_once; \ + static bool __section(".data..once") __print_once; \ \ if (!__print_once) { \ __print_once = true; \ diff --git a/mm/internal.h b/mm/internal.h index a0b24d0055795..f773db493a99d 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -40,7 +40,7 @@ struct folio_batch; * when we specify __GFP_NOWARN. */ #define WARN_ON_ONCE_GFP(cond, gfp) ({ \ - static bool __section(".data.once") __warned; \ + static bool __section(".data..once") __warned; \ int __ret_warn_once = !!(cond); \ \ if (unlikely(!(gfp & __GFP_NOWARN) && __ret_warn_once && !__warned)) { \