The generic lazy_mmu layer now tracks whether a task is in lazy MMU
mode. As a result we no longer need a TIF flag for that purpose -
let's use the new in_lazy_mmu_mode() helper instead.
The explicit check for in_interrupt() is no longer necessary either
as in_lazy_mmu_mode() always returns false in interrupt context.
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
---
arch/arm64/include/asm/pgtable.h | 19 +++----------------
arch/arm64/include/asm/thread_info.h | 3 +--
2 files changed, 4 insertions(+), 18 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index a7d99dee3dc4..dd7ed653a20d 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -62,28 +62,16 @@ static inline void emit_pte_barriers(void)
static inline void queue_pte_barriers(void)
{
- unsigned long flags;
-
- if (in_interrupt()) {
- emit_pte_barriers();
- return;
- }
-
- flags = read_thread_flags();
-
- if (flags & BIT(TIF_LAZY_MMU)) {
+ if (in_lazy_mmu_mode()) {
/* Avoid the atomic op if already set. */
- if (!(flags & BIT(TIF_LAZY_MMU_PENDING)))
+ if (!test_thread_flag(TIF_LAZY_MMU_PENDING))
set_thread_flag(TIF_LAZY_MMU_PENDING);
} else {
emit_pte_barriers();
}
}
-static inline void arch_enter_lazy_mmu_mode(void)
-{
- set_thread_flag(TIF_LAZY_MMU);
-}
+static inline void arch_enter_lazy_mmu_mode(void) {}
static inline void arch_flush_lazy_mmu_mode(void)
{
@@ -94,7 +82,6 @@ static inline void arch_flush_lazy_mmu_mode(void)
static inline void arch_leave_lazy_mmu_mode(void)
{
arch_flush_lazy_mmu_mode();
- clear_thread_flag(TIF_LAZY_MMU);
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index f241b8601ebd..4ff8da0767d9 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -84,8 +84,7 @@ void arch_setup_new_exec(void);
#define TIF_SME_VL_INHERIT 28 /* Inherit SME vl_onexec across exec */
#define TIF_KERNEL_FPSTATE 29 /* Task is in a kernel mode FPSIMD section */
#define TIF_TSC_SIGSEGV 30 /* SIGSEGV on counter-timer access */
-#define TIF_LAZY_MMU 31 /* Task in lazy mmu mode */
-#define TIF_LAZY_MMU_PENDING 32 /* Ops pending for lazy mmu mode exit */
+#define TIF_LAZY_MMU_PENDING 31 /* Ops pending for lazy mmu mode exit */
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
--
2.51.2On 24/11/25 6:52 PM, Kevin Brodsky wrote:
> The generic lazy_mmu layer now tracks whether a task is in lazy MMU
> mode. As a result we no longer need a TIF flag for that purpose -
> let's use the new in_lazy_mmu_mode() helper instead.
>
> The explicit check for in_interrupt() is no longer necessary either
> as in_lazy_mmu_mode() always returns false in interrupt context.
>
> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
> ---
> arch/arm64/include/asm/pgtable.h | 19 +++----------------
> arch/arm64/include/asm/thread_info.h | 3 +--
> 2 files changed, 4 insertions(+), 18 deletions(-)
>
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index a7d99dee3dc4..dd7ed653a20d 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -62,28 +62,16 @@ static inline void emit_pte_barriers(void)
>
> static inline void queue_pte_barriers(void)
> {
> - unsigned long flags;
> -
> - if (in_interrupt()) {
> - emit_pte_barriers();
> - return;
> - }
> -
> - flags = read_thread_flags();
> -
> - if (flags & BIT(TIF_LAZY_MMU)) {
> + if (in_lazy_mmu_mode()) {
> /* Avoid the atomic op if already set. */
> - if (!(flags & BIT(TIF_LAZY_MMU_PENDING)))
> + if (!test_thread_flag(TIF_LAZY_MMU_PENDING))
A small nit - will it be better not to use test_thread_flag() here and just
keep checking flags like earlier to avoid non-related changes. Although not
a problem TBH.
> set_thread_flag(TIF_LAZY_MMU_PENDING);
> } else {
> emit_pte_barriers();
> }
> }
>
> -static inline void arch_enter_lazy_mmu_mode(void)
> -{
> - set_thread_flag(TIF_LAZY_MMU);
> -}
> +static inline void arch_enter_lazy_mmu_mode(void) {}
>
> static inline void arch_flush_lazy_mmu_mode(void)
> {
> @@ -94,7 +82,6 @@ static inline void arch_flush_lazy_mmu_mode(void)
> static inline void arch_leave_lazy_mmu_mode(void)
> {
> arch_flush_lazy_mmu_mode();
> - clear_thread_flag(TIF_LAZY_MMU);
> }
>
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
> index f241b8601ebd..4ff8da0767d9 100644
> --- a/arch/arm64/include/asm/thread_info.h
> +++ b/arch/arm64/include/asm/thread_info.h
> @@ -84,8 +84,7 @@ void arch_setup_new_exec(void);
> #define TIF_SME_VL_INHERIT 28 /* Inherit SME vl_onexec across exec */
> #define TIF_KERNEL_FPSTATE 29 /* Task is in a kernel mode FPSIMD section */
> #define TIF_TSC_SIGSEGV 30 /* SIGSEGV on counter-timer access */
> -#define TIF_LAZY_MMU 31 /* Task in lazy mmu mode */
> -#define TIF_LAZY_MMU_PENDING 32 /* Ops pending for lazy mmu mode exit */
> +#define TIF_LAZY_MMU_PENDING 31 /* Ops pending for lazy mmu mode exit */
>
> #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
> #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
LGTM.
Hence with or without the 'flags' changes in queue_pte_barriers() above.
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
On 12/4/25 07:52, Anshuman Khandual wrote:
> On 24/11/25 6:52 PM, Kevin Brodsky wrote:
>> The generic lazy_mmu layer now tracks whether a task is in lazy MMU
>> mode. As a result we no longer need a TIF flag for that purpose -
>> let's use the new in_lazy_mmu_mode() helper instead.
>>
>> The explicit check for in_interrupt() is no longer necessary either
>> as in_lazy_mmu_mode() always returns false in interrupt context.
>>
>> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
>> ---
>> arch/arm64/include/asm/pgtable.h | 19 +++----------------
>> arch/arm64/include/asm/thread_info.h | 3 +--
>> 2 files changed, 4 insertions(+), 18 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
>> index a7d99dee3dc4..dd7ed653a20d 100644
>> --- a/arch/arm64/include/asm/pgtable.h
>> +++ b/arch/arm64/include/asm/pgtable.h
>> @@ -62,28 +62,16 @@ static inline void emit_pte_barriers(void)
>>
>> static inline void queue_pte_barriers(void)
>> {
>> - unsigned long flags;
>> -
>> - if (in_interrupt()) {
>> - emit_pte_barriers();
>> - return;
>> - }
>> -
>> - flags = read_thread_flags();
>> -
>> - if (flags & BIT(TIF_LAZY_MMU)) {
>> + if (in_lazy_mmu_mode()) {
>> /* Avoid the atomic op if already set. */
>> - if (!(flags & BIT(TIF_LAZY_MMU_PENDING)))
>> + if (!test_thread_flag(TIF_LAZY_MMU_PENDING))
>
> A small nit - will it be better not to use test_thread_flag() here and just
> keep checking flags like earlier to avoid non-related changes. Although not
> a problem TBH.
I'd assume the existing code wanted to avoid fetching the flags two
times? So switching to test_thread_flag() should be fine now.
--
Cheers
David
On 11/24/25 14:22, Kevin Brodsky wrote: > The generic lazy_mmu layer now tracks whether a task is in lazy MMU > mode. As a result we no longer need a TIF flag for that purpose - > let's use the new in_lazy_mmu_mode() helper instead. > > The explicit check for in_interrupt() is no longer necessary either > as in_lazy_mmu_mode() always returns false in interrupt context. > > Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> > --- Nothing jumped at me Acked-by: David Hildenbrand (Red Hat) <david@kernel.org> -- Cheers David
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