Date: Mon, 18 Dec 1995 07:58:18 +0100 (MET) From: aagero@aage.aage.priv.no To: FreeBSD-gnats-submit@freebsd.org Subject: kern/901: busy pages get free'd by vm_page_free Message-ID: <199512180658.HAA12860@birk04.studby.uio.no> Resent-Message-ID: <199512180700.XAA07630@freefall.freebsd.org>
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>Number: 901
>Category: kern
>Synopsis: vm_page_free frees wrong pages in vfs_bio.c
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sun Dec 17 23:00:01 PST 1995
>Last-Modified:
>Originator: Åge Røbekk
>Organization:
>Release: FreeBSD 2.2-CURRENT i386
>Environment:
FreeBSD-CURRENT 14. dec. sources.
>Description:
vm_page_free() in vfs_bio.c has an incorrent index of the free(?) pages. When
vm_hold_free_pages() calls vm_page_free() it points to the wrong page due to
the index being a signed datatype.
>How-To-Repeat:
Do a lot of activity, in order to get the paging moving. Usually ls -lR / has
been sufficient.
>Fix:
Apply the included patch.
--- kern/vfs_bio.c Sun Dec 17 02:51:17 1995
+++ kern/vfs_bio.c~ Sun Dec 17 02:51:04 1995
@@ -1634,7 +1634,7 @@
vm_offset_t to = round_page(toa);
for (pg = from; pg < to; pg += PAGE_SIZE) {
- int index = ((caddr_t) pg - bp->b_data) >> PAGE_SHIFT;
+ unsigned int index = ((caddr_t) pg - bp->b_data) >> PAGE_SHIFT;
p = bp->b_pages[index];
bp->b_pages[index] = 0;
pmap_kremove(pg);
>Audit-Trail:
>Unformatted:
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