Hi,
I think Stephen C. Tweedie has some considerations about the cache
flushing calls on do_swap_page().
Stephen?
On Wed, 27 Jun 2001, NIIBE Yutaka wrote:
> Hello Marcelo,
>
> This is follow-up to the mail in February. You may perhaps forget the
> context, it's the bug of MM about cache flushing for swapped-in-pages.
> I see this bug on SuperH port (SH-4).
>
> I think that we have this issue on the machine whose flush_dcache_page()
> is defined. In current code, the cache aren't flushed for
> the asynchronously-swapped-in pages which is cached in swap cache.
> This is the problem.
>
> Marcelo Tosatti writes:
> > Yet another thing (1) on end_buffer_io_async() to handle a case which is
> > only true for a specific user of it. Since the other special case handling
> > is for swap IO too, I think a separate IO end operation for swap would be
> > interesting.
> >
> > (1) The current one is SetPageDecrAfter handling.
>
> How about this? I've updated MM bugzilla already.
>
> 2001-06-26 NIIBE Yutaka <[EMAIL PROTECTED]>
>
> * include/linux/mm.h (PG_flush_after, PageFlushAfter,
> SetPageFlushAfter, PageTestandClearFlushAfter): New bit.
> * mm/page_io.c (rw_swap_page_base): Set flush-after bit.
> * fs/buffer.c (end_buffer_io_async): Implement flush-ing
> with PG_flush_after.
>
> * mm/memory.c (do_swap_page): Remove flush-ing the page.
>
> diff -ruNp --exclude=CVS --exclude=.cvsignore v2.4.6-pre5/fs/buffer.c
>kernel/fs/buffer.c
> --- v2.4.6-pre5/fs/buffer.c Mon Jun 25 18:48:07 2001
> +++ kernel/fs/buffer.c Tue Jun 26 15:11:17 2001
> @@ -831,6 +831,9 @@ static void end_buffer_io_async(struct b
> if (PageTestandClearDecrAfter(page))
> atomic_dec(&nr_async_pages);
>
> + if (PageTestandClearFlushAfter(page))
> + flush_dcache_page(page);
> +
> UnlockPage(page);
>
> return;
> diff -ruNp --exclude=CVS --exclude=.cvsignore v2.4.6-pre5/include/linux/mm.h
>kernel/include/linux/mm.h
> --- v2.4.6-pre5/include/linux/mm.h Mon Jun 25 18:48:09 2001
> +++ kernel/include/linux/mm.h Tue Jun 26 14:58:56 2001
> @@ -282,6 +282,7 @@ typedef struct page {
> #define PG_inactive_clean 11
> #define PG_highmem 12
> #define PG_checked 13 /* kill me in 2.5.<early>. */
> +#define PG_flush_after 14
> /* bits 21-29 unused */
> #define PG_arch_1 30
> #define PG_reserved 31
> @@ -364,6 +365,10 @@ static inline void set_page_dirty(struct
>
> #define SetPageReserved(page) set_bit(PG_reserved, &(page)->flags)
> #define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
> +
> +#define PageFlushAfter(page) test_bit(PG_flush_after, &(page)->flags)
> +#define SetPageFlushAfter(page) set_bit(PG_flush_after, &(page)->flags)
> +#define PageTestandClearFlushAfter(page) test_and_clear_bit(PG_flush_after,
>&(page)->flags)
>
> /*
> * Error return values for the *_nopage functions
> diff -ruNp --exclude=CVS --exclude=.cvsignore v2.4.6-pre5/mm/memory.c
>kernel/mm/memory.c
> --- v2.4.6-pre5/mm/memory.c Mon Jun 25 18:48:10 2001
> +++ kernel/mm/memory.c Tue Jun 26 14:48:15 2001
> @@ -1109,8 +1109,6 @@ static int do_swap_page(struct mm_struct
> return -1;
> }
> wait_on_page(page);
> - flush_page_to_ram(page);
> - flush_icache_page(vma, page);
> }
>
> /*
> diff -ruNp --exclude=CVS --exclude=.cvsignore v2.4.6-pre5/mm/page_io.c
>kernel/mm/page_io.c
> --- v2.4.6-pre5/mm/page_io.c Mon Apr 30 16:15:32 2001
> +++ kernel/mm/page_io.c Tue Jun 26 15:01:00 2001
> @@ -50,6 +50,7 @@ static int rw_swap_page_base(int rw, swp
>
> if (rw == READ) {
> ClearPageUptodate(page);
> + SetPageFlushAfter(page);
> kstat.pswpin++;
> } else
> kstat.pswpout++;
> --
>
-
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