Date: Mon, 20 Jan 2014 18:40:05 GMT From: dfilter@FreeBSD.ORG (dfilter service) To: freebsd-ia64@FreeBSD.org Subject: Re: kern/183227: commit references a PR Message-ID: <201401201840.s0KIe5Ga005291@freefall.freebsd.org>
next in thread | raw e-mail | index | archive | help
The following reply was made to PR kern/183227; it has been noted by GNATS. From: dfilter@FreeBSD.ORG (dfilter service) To: bug-followup@FreeBSD.org Cc: Subject: Re: kern/183227: commit references a PR Date: Mon, 20 Jan 2014 18:37:47 +0000 (UTC) Author: marcel Date: Mon Jan 20 18:37:35 2014 New Revision: 260914 URL: http://svnweb.freebsd.org/changeset/base/260914 Log: In pmap_set_pte(), make sure to enforce ordering by inserting a memory fence. Under system load, the CPU has been found to change the order by which the stores are made visible. When the tag is made visible before the other TLB values, other CPUs may use the invalid TLB values and do bad things. While here (i.e. not a fix) don't return errors from pmap_remove_vhpt() to callers of pmap_remove_pte(). Those callers don't check the return value and as such don't do what is needed to keep a consistent state. More importantly, pmap_remove_vhpt() can't really have an error without it indicating something unintended. Using KASSERT is therefore better. PR: 182999, 183227 Modified: head/sys/ia64/ia64/pmap.c Modified: head/sys/ia64/ia64/pmap.c ============================================================================== --- head/sys/ia64/ia64/pmap.c Mon Jan 20 18:15:06 2014 (r260913) +++ head/sys/ia64/ia64/pmap.c Mon Jan 20 18:37:35 2014 (r260914) @@ -1303,6 +1303,8 @@ pmap_set_pte(struct ia64_lpte *pte, vm_o pte->itir = PAGE_SHIFT << 2; + ia64_mf(); + pte->tag = ia64_ttag(va); } @@ -1321,8 +1323,8 @@ pmap_remove_pte(pmap_t pmap, struct ia64 * First remove from the VHPT. */ error = pmap_remove_vhpt(va); - if (error) - return (error); + KASSERT(error == 0, ("%s: pmap_remove_vhpt returned %d", + __func__, error)); pmap_invalidate_page(va); _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscribe@freebsd.org"
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201401201840.s0KIe5Ga005291>