Messages in this thread |  | | Date | Mon, 14 May 2001 19:05:35 -0300 (BRT) | From | Marcelo Tosatti <> | Subject | Re: page_launder() bug |
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On Sun, 13 May 2001, Linus Torvalds wrote:
> > On Sun, 13 May 2001, Rik van Riel wrote: > > > > This means that the swapin path (and the same path for > > other pagecache pages) doesn't take the page lock and > > the page lock doesn't protect us from other people using > > the page while we have it locked. > > You can test for swap cache deadness without holding the page cache lock: > if the swap count is 1, then we know that nobody else has this swap entry > in its page tables, and thus there can not be any concurrent lookups > either. > > Now, it may well be that we need to make sure that there is some proper > ordering (nobody must decrement the swap count before they increment the > page count or something). I think that is the case anyway (and I _think_ > that everybody that mucks with the swap count always hold the page count - > this might be a good thing to check).
Swapin readahead _first_ increases the swap map count for the given page and then increases the page count.
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