The test driver uses an xa_array to store virtual to physical address translations for a simulated hardware device. The MMU notifier invalidation callback is used to keep the table consistent with the CPU page table and is frequently called only for a page or two. However, if the test process exits unexpectedly or is killed, the range can be [0..ULONG_MAX] in which case calling xa_erase() for every possible PFN results in CPU timeouts. Use xa_for_each_range() to efficiently erase entries in the range.
Signed-off-by: Ralph Campbell rcampbell@nvidia.com ---
This patch is based on Jason Gunthorpe's hmm tree and should be folded into the ("mm/hmm/test: add selftest driver for HMM") patch once this patch is reviewed, etc.
v1 -> v2: Use xa_for_each_range() instead of special casing [0..ULONG_MAX].
lib/test_hmm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/lib/test_hmm.c b/lib/test_hmm.c index 8b36c26b717b..5c1858e325ba 100644 --- a/lib/test_hmm.c +++ b/lib/test_hmm.c @@ -196,13 +196,15 @@ static void dmirror_do_update(struct dmirror *dmirror, unsigned long start, unsigned long end) { unsigned long pfn; + void *entry;
/* * The XArray doesn't hold references to pages since it relies on * the mmu notifier to clear page pointers when they become stale. * Therefore, it is OK to just clear the entry. */ - for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) + xa_for_each_range(&dmirror->pt, pfn, entry, start >> PAGE_SHIFT, + end >> PAGE_SHIFT) xa_erase(&dmirror->pt, pfn); }