[prev in list] [next in list] [prev in thread] [next in thread] 

List:       linux-kernel
Subject:    Re: [Patch] shm bug introduced with pagecache in 2.3.11
From:       Manfred Spraul <manfreds () colorfullife ! com>
Date:       1999-11-25 18:08:55
[Download RAW message or body]

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

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

[prev in list] [next in list] [prev in thread] [next in thread]