Re: Oops in __free_pages_ok (pre7-1) (Long) (backtrace)

[Linus Torvalds <torvalds@transmeta.com>]

On Wed, 3 May 2000, Rajagopal Ananthanarayanan wrote:
> 
> One quick comment: Looking at this part of the diff to mm/vmscan.c:
> 
> ----------
> @@ -138,6 +139,7 @@
>                 flush_tlb_page(vma, address);
>                 vmlist_access_unlock(vma->vm_mm);
>                 error = swapout(page, file);
> +               UnlockPage(page);
>                 if (file) fput(file);
>                 if (!error)
>                         goto out_free_success;
> -----------------
> 
> Didn't you mean the UnlockPage() to go before swapout(...)?
> For example, one of the swapout routines, filemap_write_page()
> expects the page to be unlocked. If called with page locked,
> I'd expect a "double-trip" dead-lock. Right?

Nope. I changed swap_out() so that it gets called with the page locked
(which is much more like the other VM routines work too). Otherwise the
first thing swap_out() would do would be to just re-lock the page,and then
you'd have a window between the caller and the callee when neither the
page lock nor the page table lock were held.

		Linus

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