Date: Thu, 12 May 2011 01:38:42 +0000 (UTC) From: Max Laier <mlaier@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-7@freebsd.org Subject: svn commit: r221796 - stable/7/sys/vm Message-ID: <201105120138.p4C1cgU4014264@svn.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: mlaier Date: Thu May 12 01:38:42 2011 New Revision: 221796 URL: http://svn.freebsd.org/changeset/base/221796 Log: MFH r221714: Another long standing vm bug found at Isilon: Fix a race between vm_object_collapse and vm_fault. Reviewed by: alc@ Modified: stable/7/sys/vm/vm_object.c Directory Properties: stable/7/sys/ (props changed) stable/7/sys/cddl/contrib/opensolaris/ (props changed) stable/7/sys/contrib/dev/acpica/ (props changed) stable/7/sys/contrib/pf/ (props changed) Modified: stable/7/sys/vm/vm_object.c ============================================================================== --- stable/7/sys/vm/vm_object.c Thu May 12 01:22:23 2011 (r221795) +++ stable/7/sys/vm/vm_object.c Thu May 12 01:38:42 2011 (r221796) @@ -1613,6 +1613,24 @@ vm_object_backing_scan(vm_object_t objec pp = vm_page_lookup(object, new_pindex); if ( + (op & OBSC_COLLAPSE_NOWAIT) != 0 && + (pp != NULL && pp->valid == 0) + ) { + /* + * The page in the parent is not (yet) valid. + * We don't know anything about the state of + * the original page. It might be mapped, + * so we must avoid the next if here. + * + * This is due to a race in vm_fault() where + * we must unbusy the original (backing_obj) + * page before we can (re)lock the parent. + * Hence we can get here. + */ + p = next; + continue; + } + if ( pp != NULL || vm_pager_has_page(object, new_pindex, NULL, NULL) ) {
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201105120138.p4C1cgU4014264>