On 06/05/2018 12:12 PM, Mel Gorman wrote: > That's fair enough. I updated part of the changelog to read > > This patch special cases anonymous pages to only flush ranges under the > page table lock if the page is in swap cache and can be potentially queued > for IO. Note that the full flush of the range being mremapped is still > flushed so TLB flushes are not eliminated entirely. > > Does that work for you? Looks good, thanks. >> I usually try to make the non-pte-modifying functions take a pte_t >> instead of 'pte_t *' to make it obvious that there no modification going >> on. Any reason not to do that here? > > No, it was just a minor saving on stack usage. We're just splitting hairs now :) but, realistically, this little helper will get inlined anyway, so it probably all generates the same code. ... >> BTW, do you want to add a tiny comment about why we do the >> trylock_page()? I assume it's because we don't want to wait on finding >> an exact answer: we just assume it is in the swap cache if the page is >> locked and flush regardless. > > It's really because calling lock_page while holding a spinlock is > eventually going to ruin your day. Hah, yeah, that'll do it. Could you comment this, too?
