Date: Sun, 10 Nov 2002 23:34:36 -0500 From: Jake Burkholder <jake@locore.ca> To: Matthew Jacob <mjacob@feral.com> Cc: "Alan L. Cox" <alc@imimic.com>, jeff@freebsd.org, cvs-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/vm uma_dbg.c Message-ID: <20021110233436.C85338@locore.ca> In-Reply-To: <Pine.BSF.4.21.0211101820030.62965-100000@beppo>; from mjacob@feral.com on Sun, Nov 10, 2002 at 06:24:42PM -0800 References: <Pine.BSF.4.21.0211101810230.62965-100000@beppo> <Pine.BSF.4.21.0211101820030.62965-100000@beppo>
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Apparently, On Sun, Nov 10, 2002 at 06:24:42PM -0800, Matthew Jacob said words to the effect of; > > > > > > > > Matt, can you try acquiring and releasing the zone mutex in > > > uma_dbg_alloc() and uma_dbg_free() instead? > > > > > > > Sure- let me look at this a little closer - I'll interrupt the make > > release and try a different approach. > > The trouble is that slab_zalloc sets value in us_freelist with the zone > lock not held. > > THe locking for falling uma_dbg_alloc and uma_dbg_free doesn't seem all > that consistent to me. > > It's getting beyond my easy reading/fixing. If there is no MI atomic > set/clear 8 (which, IMO, is kind of a bug), I'd just change us_freelist > to be an int for now. This change seemed to make a difference- but it > could be coincidence. > This would be my suggestion: Index: sys/vm/uma_core.c =================================================================== RCS file: /home/ncvs/src/sys/vm/uma_core.c,v retrieving revision 1.41 diff -u -r1.41 uma_core.c --- sys/vm/uma_core.c 1 Nov 2002 01:01:27 -0000 1.41 +++ sys/vm/uma_core.c 11 Nov 2002 04:11:38 -0000 @@ -1348,7 +1348,9 @@ ("uma_zalloc: Bucket pointer mangled.")); cache->uc_allocs++; #ifdef INVARIANTS + ZONE_LOCK(zone); uma_dbg_alloc(zone, NULL, item); + ZONE_UNLOCK(zone); #endif CPU_UNLOCK(zone, cpu); if (zone->uz_ctor) @@ -1698,10 +1700,12 @@ ("uma_zfree: Freeing to non free bucket index.")); bucket->ub_bucket[bucket->ub_ptr] = item; #ifdef INVARIANTS + ZONE_LOCK(zone); if (zone->uz_flags & UMA_ZFLAG_MALLOC) uma_dbg_free(zone, udata, item); else uma_dbg_free(zone, NULL, item); + ZONE_UNLOCK(zone); #endif CPU_UNLOCK(zone, cpu); return; uma_dbg_* are called with the zone lock held everywhere else, and the us_freelist is used with the zone lock held everywhere else as well. slab_zalloc is working on a newly created slab that doesn't have any other references, so it doesn't need to be locked until its added to the zone. Jake To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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