Date: Tue, 5 Dec 2000 13:44:23 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: Alfred Perlstein <bright@wintelcom.net> Cc: peter@FreeBSD.ORG, hackers@FreeBSD.ORG Subject: Re: phys backed shm patch. Message-ID: <200012052144.eB5LiNT86399@earth.backplane.com> References: <20001205123456.D8051@fw.wintelcom.net>
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:
:Ok, I spent quite some time trying to figure out why postgresql
:would "hang" when using the 'kern.ipc.shm_use_phys' sysctl.
:
:It finally came down to some spinlocks that were being corrupted
:in a very tiny shared memory segment.
:
:It seems like the phys_pager doesn't correctly allocate when
:given a non PAGE_SIZE'd 'size' so then I think odd stuff happens
:to the memory in the pages:
Yes, you are absolutely right. That's definitely a bug and your fix
is the correct one.
In regards to simultanious commit, unless someone makes the rules a
little more reasonable for simple bug fixes like this you'll probably
get fried for doing it by bozos who have nothing better to do with their
time.
-Matt
:Index: phys_pager.c
:===================================================================
:RCS file: /home/ncvs/src/sys/vm/phys_pager.c,v
:retrieving revision 1.3.2.1
:diff -u -u -r1.3.2.1 phys_pager.c
:--- phys_pager.c 2000/08/04 22:31:11 1.3.2.1
:+++ phys_pager.c 2000/12/05 20:13:25
:@@ -83,7 +83,7 @@
: * Allocate object and associate it with the pager.
: */
: object = vm_object_allocate(OBJT_PHYS,
:- OFF_TO_IDX(foff + size));
:+ OFF_TO_IDX(foff + PAGE_MASK + size));
: object->handle = handle;
: TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
: pager_object_list);
:
:
:I'd like to commit it to both current and stable asap (afaik no
:one uses kern.ipc.shm_use_phys anyhow, we missed the boat on
:Oracle)
:
:--
:-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
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