Messages in this thread | | | Date | Thu, 25 Nov 1999 19:08:55 +0100 | From | Manfred Spraul <> | Subject | Re: [Patch] shm bug introduced with pagecache in 2.3.11 |
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Linus Torvalds wrote: > I was planning on just depending on the sanity of the page cache on this ^^^^^^^^^ > one. page cache or page tables? if you want to rely on the page table, then pmd_alloc() and pte_alloc() could become a problem.
> Basically we have two cases: > - paging in something new ("no_page"), for which the final test is just > to test that the page table is still zero (ie we don't even need to > save any "original" value). > - paging in something old ("swap_page"), in wich case the final test is > to check that the pte is still the same as swp_entry_to_pte(entry). >
Or: we define a new value SWP_LOADING (eg SWP_ENTRY(1,0). if the pte entry is SWP_LOADING, then we just sleep. otherwise, we replace the pte with SWP_LOADING, do the actual io, and wake-up all other threads that are waiting.
-- Manfred
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