Commit 85ae87c1ad8e18a421e7448a99a42ecda183f29f
1 parent
f234012f52
percpu: fix too lazy vunmap cache flushing
In pcpu_unmap(), flushing virtual cache on vunmap can't be delayed as the page is going to be returned to the page allocator. Only TLB flushing can be put off such that vmalloc code can handle it lazily. Fix it. [ Impact: fix subtle virtual cache flush bug ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Nick Piggin <npiggin@suse.de> Cc: Ingo Molnar <mingo@elte.hu>
Showing 1 changed file with 5 additions and 6 deletions Side-by-side Diff
mm/percpu.c
| ... | ... | @@ -549,14 +549,14 @@ |
| 549 | 549 | * @chunk: chunk of interest |
| 550 | 550 | * @page_start: page index of the first page to unmap |
| 551 | 551 | * @page_end: page index of the last page to unmap + 1 |
| 552 | - * @flush: whether to flush cache and tlb or not | |
| 552 | + * @flush_tlb: whether to flush tlb or not | |
| 553 | 553 | * |
| 554 | 554 | * For each cpu, unmap pages [@page_start,@page_end) out of @chunk. |
| 555 | 555 | * If @flush is true, vcache is flushed before unmapping and tlb |
| 556 | 556 | * after. |
| 557 | 557 | */ |
| 558 | 558 | static void pcpu_unmap(struct pcpu_chunk *chunk, int page_start, int page_end, |
| 559 | - bool flush) | |
| 559 | + bool flush_tlb) | |
| 560 | 560 | { |
| 561 | 561 | unsigned int last = num_possible_cpus() - 1; |
| 562 | 562 | unsigned int cpu; |
| ... | ... | @@ -569,9 +569,8 @@ |
| 569 | 569 | * the whole region at once rather than doing it for each cpu. |
| 570 | 570 | * This could be an overkill but is more scalable. |
| 571 | 571 | */ |
| 572 | - if (flush) | |
| 573 | - flush_cache_vunmap(pcpu_chunk_addr(chunk, 0, page_start), | |
| 574 | - pcpu_chunk_addr(chunk, last, page_end)); | |
| 572 | + flush_cache_vunmap(pcpu_chunk_addr(chunk, 0, page_start), | |
| 573 | + pcpu_chunk_addr(chunk, last, page_end)); | |
| 575 | 574 | |
| 576 | 575 | for_each_possible_cpu(cpu) |
| 577 | 576 | unmap_kernel_range_noflush( |
| ... | ... | @@ -579,7 +578,7 @@ |
| 579 | 578 | (page_end - page_start) << PAGE_SHIFT); |
| 580 | 579 | |
| 581 | 580 | /* ditto as flush_cache_vunmap() */ |
| 582 | - if (flush) | |
| 581 | + if (flush_tlb) | |
| 583 | 582 | flush_tlb_kernel_range(pcpu_chunk_addr(chunk, 0, page_start), |
| 584 | 583 | pcpu_chunk_addr(chunk, last, page_end)); |
| 585 | 584 | } |