| Message ID | 20200516010424.2013-1-rcampbell@nvidia.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] mm/hmm/test: use xa_for_each_range instead of looping | expand |
On Fri, May 15, 2020 at 06:04:24PM -0700, Ralph Campbell wrote: > 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(-) I squashed this in Thanks, Jason
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); }
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(-)