Messages in this thread | | | Date | Tue, 15 Jun 2010 06:53:41 -0400 | From | Christoph Hellwig <> | Subject | Re: [PATCH 11/12] vmscan: Write out dirty pages in batch |
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> + /* > + * XXX: This is the Holy Hand Grenade of PotentiallyInvalidMapping. As > + * the page lock has been dropped by ->writepage, that mapping could > + * be anything > + */
Why is this an XXX comment?
> + /* > + * Wait on writeback if requested to. This happens when > + * direct reclaiming a large contiguous area and the > + * first attempt to free a range of pages fails. > + */ > + if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC) > + wait_on_page_writeback(page); > + > + if (!PageWriteback(page)) { > + /* synchronous write or broken a_ops? */ > + ClearPageReclaim(page); > + }
how about:
if (PageWriteback(page) { if (sync_writeback == PAGEOUT_IO_SYNC) wait_on_page_writeback(page); } else { /* synchronous write or broken a_ops? */ ClearPageReclaim(page); }
> if (!may_write_to_queue(mapping->backing_dev_info)) > return PAGE_KEEP; > > /* > + * Clean a list of pages. It is expected that all the pages on page_list have been > + * locked as part of isolation from the LRU.
A rather pointless line of 80 chars. I see the point for long string literals, but here's it's just a pain.
> + * > + * XXX: Is there a problem with holding multiple page locks like this?
I think there is. There's quite a few places that do hold multiple pages locked, but they always lock pages in increasing page->inxex order. Given that this locks basically in random order it could cause problems for those places.
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