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mm, x86/mm: Make the batched unmap TLB flush API more generic

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try_to_unmap_flush() used to open-code a rather x86-centric flush
sequence: local_flush_tlb() + flush_tlb_others().  Rearrange the
code so that the arch (only x86 for now) provides
arch_tlbbatch_add_mm() and arch_tlbbatch_flush() and the core code
calls those functions instead.

I'll want this for x86 because, to enable address space ids, I can't
support the flush_tlb_others() mode used by exising
try_to_unmap_flush() implementation with good performance.  I can
support the new API fairly easily, though.

I imagine that other architectures may be in a similar position.
Architectures with strong remote flush primitives (arm64?) may have
even worse performance problems with flush_tlb_others() the way that
try_to_unmap_flush() uses it.

Signed-off-by: Andy Lutomirski <[email protected]>
Acked-by: Kees Cook <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Sasha Levin <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/19f25a8581f9fb77876b7ff3b001f89835e34ea3.1495492063.git.luto@kernel.org
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Andy Lutomirski 2017-05-22 15:30:03 -07:00 • committed by Ingo Molnar
commit e73ad5ff2f
5 changed files with 54 additions and 18 deletions
Download patch file Download diff file Expand all files Collapse all files

16
mm/rmap.c
View file

@ -579,25 +579,13 @@ void page_unlock_anon_vma_read(struct anon_vma *anon_vma)
void try_to_unmap_flush(void)
{
struct tlbflush_unmap_batch *tlb_ubc = &current->tlb_ubc;
int cpu;
if (!tlb_ubc->flush_required)
return;
cpu = get_cpu();
if (cpumask_test_cpu(cpu, &tlb_ubc->cpumask)) {
count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
local_flush_tlb();
trace_tlb_flush(TLB_LOCAL_SHOOTDOWN, TLB_FLUSH_ALL);
}
if (cpumask_any_but(&tlb_ubc->cpumask, cpu) < nr_cpu_ids)
flush_tlb_others(&tlb_ubc->cpumask, NULL, 0, TLB_FLUSH_ALL);
cpumask_clear(&tlb_ubc->cpumask);
arch_tlbbatch_flush(&tlb_ubc->arch);
tlb_ubc->flush_required = false;
tlb_ubc->writable = false;
put_cpu();
}
/* Flush iff there are potentially writable TLB entries that can race with IO */
@ -613,7 +601,7 @@ static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable)
{
struct tlbflush_unmap_batch *tlb_ubc = &current->tlb_ubc;
cpumask_or(&tlb_ubc->cpumask, &tlb_ubc->cpumask, mm_cpumask(mm));
arch_tlbbatch_add_mm(&tlb_ubc->arch, mm);
tlb_ubc->flush_required = true;
/*