Date: Sun, 08 Nov 1998 11:24:08 -0800 From: David Greenman <dg@root.com> To: Dmitrij Tejblum <dima@tejblum.dnttm.rssi.ru> Cc: Eivind Eklund <eivind@yes.no>, John Fieber <jfieber@indiana.edu>, current@FreeBSD.ORG Subject: Re: The infamous dying daemons bug Message-ID: <199811081924.LAA06586@root.com> In-Reply-To: Your message of "Sun, 08 Nov 1998 21:06:29 %2B0300." <199811081806.VAA00888@tejblum.dnttm.rssi.ru>
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>Eivind Eklund wrote:
>>
>> Oh, and another aspect: This suddenly started happening. It has been
>> stable for 3/4 of a year, and then suddenly started happening
>> reproducably one day, after a kernel update while John was doing his
>> changes.
>
>Please don't tell anyone, but I am almost convinced that the bug is
>here:
>
>-----swap_pager.c, line 1132------
> /*
> * If we're out of swap space, then attempt to free
> * some whenever multiple pages are brought in. We
> * must set the dirty bits so that the page contents
> * will be preserved.
> */
> if (SWAPLOW ||
> (vm_swap_size < btodb((cnt.v_page_count - cnt.v_wire_count)) * PAGE_SIZE)) {
> for (i = 0; i < count; i++) {
> m[i]->dirty = VM_PAGE_BITS_ALL;
> }
> swap_pager_freespace(object,
> m[0]->pindex + paging_offset, count);
> }
>------------------------------------
>If I sysctl out the call to swap_pager_freespace, all symptoms
>disappear. This code activates at about the time when the "suggest more
>swap space" message printed. IIRC, it was introduced by John Dyson this
>winter.
>
>(Perhaps, the code just triggers a bug elsewhere... No idea what is
>wrong).
I don't see anything wrong with it, but if it is the cause of the
problem, it can safely be removed. I'd suggest that people #if 0 out
the code and see if the problem completely vanishes.
-DG
David Greenman
Co-founder/Principal Architect, The FreeBSD Project
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