Date: Thu, 04 Mar 2004 21:28:56 -0600 From: "Alan L. Cox" <alc@imimic.com> To: Marcel Moolenaar <marcel@xcllnt.net> Cc: Nate Lawson <nate@root.org> Subject: Re: bug in vm_contig.c? [was: Re: ACPI crash with recent changes] Message-ID: <4047F3F8.1080207@imimic.com> In-Reply-To: <20040305025524.GA601@dhcp01.pn.xcllnt.net> References: <20040304025223.GA622@dhcp01.pn.xcllnt.net> <20040304161108.U26303@root.org> <20040305025524.GA601@dhcp01.pn.xcllnt.net>
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Please test the attached patch instead. In order to avoid a race
condition, it is necessary for the loop to begin with "start" rather
than "start + 1". What is both unnecessary and wrong is the physical
contiguity check. (My bad. :-() In other words, the test that the page
is still free must be repeated because of the dropping of the free page
queue lock, but contiguity once true is always true.
Regards,
Alan
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filename="vm_contig.c-bug-fix"
Index: vm/vm_contig.c
===================================================================
RCS file: /home/ncvs/src/sys/vm/vm_contig.c,v
retrieving revision 1.31
diff -u -r1.31 vm_contig.c
--- vm/vm_contig.c 2 Mar 2004 08:25:58 -0000 1.31
+++ vm/vm_contig.c 5 Mar 2004 03:08:17 -0000
@@ -232,9 +232,7 @@
mtx_lock_spin(&vm_page_queue_free_mtx);
for (i = start; i < (start + size / PAGE_SIZE); i++) {
pqtype = pga[i].queue - pga[i].pc;
- if ((VM_PAGE_TO_PHYS(&pga[i]) !=
- (VM_PAGE_TO_PHYS(&pga[i - 1]) + PAGE_SIZE)) ||
- (pqtype != PQ_FREE)) {
+ if (pqtype != PQ_FREE) {
start++;
goto again;
}
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