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arch, mm: Remove tlb_fast_mode()

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Since the introduction of preemptible mmu_gather TLB fast mode has been
broken. TLB fast mode relies on there being absolutely no concurrency;
it frees pages first and invalidates TLBs later.

However now we can get concurrency and stuff goes *bang*.

This patch removes all tlb_fast_mode() code; it was found the better
option vs trying to patch the hole by entangling tlb invalidation with
the scheduler.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Tony Luck <tony.luck@intel.com>
Reported-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Peter Zijlstra
2013-06-05 12:26:50 +02:00
committed by Linus Torvalds
parent 2c95523c0f
commit 29eb77825c
4 changed files with 13 additions and 81 deletions
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9
mm/memory.c
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@ -220,7 +220,6 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
tlb->start = -1UL;
tlb->end = 0;
tlb->need_flush = 0;
tlb->fast_mode = (num_possible_cpus() == 1);
tlb->local.next = NULL;
tlb->local.nr = 0;
tlb->local.max = ARRAY_SIZE(tlb->__pages);
@ -244,9 +243,6 @@ void tlb_flush_mmu(struct mmu_gather *tlb)
tlb_table_flush(tlb);
#endif
if (tlb_fast_mode(tlb))
return;
for (batch = &tlb->local; batch; batch = batch->next) {
free_pages_and_swap_cache(batch->pages, batch->nr);
batch->nr = 0;
@ -288,11 +284,6 @@ int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
VM_BUG_ON(!tlb->need_flush);
if (tlb_fast_mode(tlb)) {
free_page_and_swap_cache(page);
return 1; /* avoid calling tlb_flush_mmu() */
}
batch = tlb->active;
batch->pages[batch->nr++] = page;
if (batch->nr == batch->max) {