Date: Fri, 9 Aug 2013 13:41:56 -0700 From: Alan Cox <alc@rice.edu> To: John Baldwin <jhb@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, "David E. O'Brien" <obrien@freebsd.org> Subject: Re: svn commit: r254150 - head/sys/vm Message-ID: <DD399E2C-B4B2-41B3-9C64-CD73FC3B5040@rice.edu> In-Reply-To: <201308091639.30727.jhb@freebsd.org> References: <201308091643.r79GhoWx023884@svn.freebsd.org> <201308091556.47535.jhb@freebsd.org> <DA97389E-DAB5-4DB6-BB52-417CDBBB0BF9@rice.edu> <201308091639.30727.jhb@freebsd.org>
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On Aug 9, 2013, at 1:39 PM, John Baldwin wrote: > On Friday, August 09, 2013 4:34:36 pm Alan Cox wrote: >>=20 >> On Aug 9, 2013, at 12:56 PM, John Baldwin wrote: >>=20 >>> On Friday, August 09, 2013 12:43:50 pm David E. O'Brien wrote: >>>> Author: obrien >>>> Date: Fri Aug 9 16:43:50 2013 >>>> New Revision: 254150 >>>> URL: http://svnweb.freebsd.org/changeset/base/254150 >>>>=20 >>>> Log: >>>> Add missing 'VPO_BUSY' from r254141 to fix kernel build break. >>>>=20 >>>> Modified: >>>> head/sys/vm/vm_page.h >>>=20 >>> This can't possibly be correct as r254138 just removed this flag. = If it=20 > isn't=20 >>> obvious how to fix the uses added back in r254141, then r254141 = should be=20 >>> reverted instead. >>>=20 >>> Hmm, looking at the relevant bits of r254141, it doesn't look = obvious: >>>=20 >>> + /* Detach the old page from the resident tailq. */ >>> + TAILQ_REMOVE(&object->memq, mold, listq); >>> + vm_page_lock(mold); >>=20 >> Replace the next four lines with >>=20 >> vm_page_xunbusy(mold); >=20 > That is going to recurse on vm_page_lock(), is that ok? >=20 No, it's not. >>> + if (mold->oflags & VPO_BUSY) { >>> + mold->oflags &=3D ~VPO_BUSY; >>> + vm_page_flash(mold); >>> + } >>>=20 >>> Since nothing is setting this flag, this can't possibly work = correctly=20 >>> currently. I wouldn't boot a top-of-tree kernel right now. :( >>>=20 >>> --=20 >>> John Baldwin >>>=20 >>=20 >>=20 >=20 > --=20 > John Baldwin >=20
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