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x86/mm: Give each mm TLB flush generation a unique ID

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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.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski
2017-06-29 08:53:15 -07:00
committed by Ingo Molnar
parent 4422d80ed7
commit f39681ed0f
4 changed files with 51 additions and 4 deletions
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6
arch/x86/mm/tlb.c
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@@ -28,6 +28,8 @@
* Implement flush IPI by CALL_FUNCTION_VECTOR, Alex Shi
*/
atomic64_t last_mm_ctx_id = ATOMIC64_INIT(1);
void leave_mm(int cpu)
{
struct mm_struct *loaded_mm = this_cpu_read(cpu_tlbstate.loaded_mm);
@@ -250,8 +252,8 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
cpu = get_cpu();
/* Synchronize with switch_mm. */
smp_mb();
/* This is also a barrier that synchronizes with switch_mm(). */
inc_mm_tlb_gen(mm);
/* Should we flush just the requested range? */
if ((end != TLB_FLUSH_ALL) &&