4.4-stable review patch. If anyone has any objections, please let me know.
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From: Andy Lutomirski luto@kernel.org
commit f39681ed0f48498b80455095376f11535feea332 upstream.
This adds two new variables to mmu_context_t: ctx_id and tlb_gen. ctx_id uniquely identifies the mm_struct and will never be reused. For a given mm_struct (and hence ctx_id), tlb_gen is a monotonic count of the number of times that a TLB flush has been requested. The pair (ctx_id, tlb_gen) can be used as an identifier for TLB flush actions and will be used in subsequent patches to reliably determine whether all needed TLB flushes have occurred on a given CPU.
This patch is split out for ease of review. By itself, it has no real effect other than creating and updating the new variables.
Signed-off-by: Andy Lutomirski luto@kernel.org Reviewed-by: Nadav Amit nadav.amit@gmail.com Reviewed-by: Thomas Gleixner tglx@linutronix.de Cc: Andrew Morton akpm@linux-foundation.org Cc: Arjan van de Ven arjan@linux.intel.com Cc: Borislav Petkov bp@alien8.de Cc: Dave Hansen dave.hansen@intel.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Mel Gorman mgorman@suse.de Cc: Peter Zijlstra peterz@infradead.org Cc: Rik van Riel riel@redhat.com Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/413a91c24dab3ed0caa5f4e4d017d87b0857f920.1498751203... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Tim Chen tim.c.chen@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Srivatsa S. Bhat srivatsa@csail.mit.edu Reviewed-by: Matt Helsley (VMware) matt.helsley@gmail.com Reviewed-by: Alexey Makhalov amakhalov@vmware.com Reviewed-by: Bo Gan ganb@vmware.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org ---
arch/x86/include/asm/mmu.h | 15 +++++++++++++-- arch/x86/include/asm/mmu_context.h | 4 ++++ arch/x86/mm/tlb.c | 2 ++ 3 files changed, 19 insertions(+), 2 deletions(-)
--- a/arch/x86/include/asm/mmu.h +++ b/arch/x86/include/asm/mmu.h @@ -3,12 +3,18 @@
#include <linux/spinlock.h> #include <linux/mutex.h> +#include <linux/atomic.h>
/* - * The x86 doesn't have a mmu context, but - * we put the segment information here. + * x86 has arch-specific MMU state beyond what lives in mm_struct. */ typedef struct { + /* + * ctx_id uniquely identifies this mm_struct. A ctx_id will never + * be reused, and zero is not a valid ctx_id. + */ + u64 ctx_id; + #ifdef CONFIG_MODIFY_LDT_SYSCALL struct ldt_struct *ldt; #endif @@ -24,6 +30,11 @@ typedef struct { atomic_t perf_rdpmc_allowed; /* nonzero if rdpmc is allowed */ } mm_context_t;
+#define INIT_MM_CONTEXT(mm) \ + .context = { \ + .ctx_id = 1, \ + } + void leave_mm(int cpu);
#endif /* _ASM_X86_MMU_H */ --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -11,6 +11,9 @@ #include <asm/tlbflush.h> #include <asm/paravirt.h> #include <asm/mpx.h> + +extern atomic64_t last_mm_ctx_id; + #ifndef CONFIG_PARAVIRT static inline void paravirt_activate_mm(struct mm_struct *prev, struct mm_struct *next) @@ -105,6 +108,7 @@ static inline void enter_lazy_tlb(struct static inline int init_new_context(struct task_struct *tsk, struct mm_struct *mm) { + mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id); init_new_context_ldt(tsk, mm); return 0; } --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -29,6 +29,8 @@ * Implement flush IPI by CALL_FUNCTION_VECTOR, Alex Shi */
+atomic64_t last_mm_ctx_id = ATOMIC64_INIT(1); + struct flush_tlb_info { struct mm_struct *flush_mm; unsigned long flush_start;