Date: Wed, 30 Jul 2014 23:26:34 +0200 From: Andreas Tobler <andreast@FreeBSD.org> To: Alan Cox <alc@rice.edu>, Alan Cox <alc@FreeBSD.org>, src-committers@FreeBSD.org, svn-src-all@FreeBSD.org, svn-src-head@FreeBSD.org Subject: Re: svn commit: r269134 - head/sys/vm Message-ID: <53D9630A.5050500@FreeBSD.org> In-Reply-To: <53D960E9.50905@rice.edu> References: <201407261810.s6QIAIIj049439@svn.freebsd.org> <53D9406A.3060101@FreeBSD.org> <53D94BAF.8050102@rice.edu> <53D94D73.3050808@rice.edu> <53D95265.9010406@FreeBSD.org> <53D960E9.50905@rice.edu>
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On 30.07.14 23:17, Alan Cox wrote: > On 07/30/2014 15:15, Andreas Tobler wrote: >> On 30.07.14 21:54, Alan Cox wrote: >>> On 07/30/2014 14:46, Alan Cox wrote: >>>> On 07/30/2014 13:58, Andreas Tobler wrote: >>>>> Hi Alan, >>>>> >>>>> On 26.07.14 20:10, Alan Cox wrote: >>>>>> Author: alc >>>>>> Date: Sat Jul 26 18:10:18 2014 >>>>>> New Revision: 269134 >>>>>> URL: http://svnweb.freebsd.org/changeset/base/269134 >>>>>> >>>>>> Log: >>>>>> When unwiring a region of an address space, do not assume that >>>>>> the >>>>>> underlying physical pages are mapped by the pmap. If, for >>>>>> example, the >>>>>> application has performed an mprotect(..., PROT_NONE) on any part >>>>>> of the >>>>>> wired region, then those pages will no longer be mapped by the >>>>>> pmap. >>>>>> So, using the pmap to lookup the wired pages in order to >>>>>> unwire them >>>>>> doesn't always work, and when it doesn't work wired pages are >>>>>> leaked. >>>>>> >>>>>> To avoid the leak, introduce and use a new function >>>>>> vm_object_unwire() >>>>>> that locates the wired pages by traversing the object and its >>>>>> backing >>>>>> objects. >>>>>> >>>>>> At the same time, switch from using pmap_change_wiring() to the >>>>>> recently >>>>>> introduced function pmap_unwire() for unwiring the region's >>>>>> mappings. >>>>>> pmap_unwire() is faster, because it operates a range of virtual >>>>>> addresses >>>>>> rather than a single virtual page at a time. Moreover, by >>>>>> operating on >>>>>> a range, it is superpage friendly. It doesn't waste time >>>>>> performing >>>>>> unnecessary demotions. >>>>>> >>>>>> Reported by: markj >>>>>> Reviewed by: kib >>>>>> Tested by: pho, jmg (arm) >>>>>> Sponsored by: EMC / Isilon Storage Division >>>>> This commit brings my 32- and 64-bit PowerMac's into panic. >>>>> Unfortunately I'm not able to give you a backtrace in the form of a >>>>> textdump nor of a core dump. >>>>> >>>>> The only thing I have is this picture: >>>>> >>>>> http://people.freebsd.org/~andreast/r269134_panic.jpg >>>>> >>>>> Exactly this revision gives a panic and breaks the textdump/coredump >>>>> facility. >>>>> >>>>> How can I help debugging? >>>>> >>>> It appears to me that moea64_pvo_enter() had a pre-existing bug that >>>> got >>>> tickled by this change. Specifically, moea64_pvo_enter() doesn't set >>>> the PVO_WIRED flag when an unwired mapping already exists. It just >>>> returns with the mapping still in an unwired state. Consequently, when >>>> pmap_unwire() finally runs, it doesn't find a wired mapping. >>>> >>>> Try this: >>>> >>>> Index: powerpc/aim/mmu_oea64.c >>>> =================================================================== >>>> --- powerpc/aim/mmu_oea64.c (revision 269127) >>>> +++ powerpc/aim/mmu_oea64.c (working copy) >>>> @@ -2274,7 +2274,8 @@ moea64_pvo_enter(mmu_t mmu, pmap_t pm, uma_zone_t >>>> if (pvo->pvo_pmap == pm && PVO_VADDR(pvo) == va) { >>>> if ((pvo->pvo_pte.lpte.pte_lo & LPTE_RPGN) >>>> == pa && >>>> (pvo->pvo_pte.lpte.pte_lo & (LPTE_NOEXEC | >>>> LPTE_PP)) >>>> - == (pte_lo & (LPTE_NOEXEC | LPTE_PP))) { >>>> + == (pte_lo & (LPTE_NOEXEC | LPTE_PP)) && >>>> + ((pvo->pvo_vaddr ^ flags) & PVO_WIRED)) { >>>> if (!(pvo->pvo_pte.lpte.pte_hi & >>>> LPTE_VALID)) { >>>> /* Re-insert if spilled */ >>>> i = MOEA64_PTE_INSERT(mmu, >>>> ptegidx, >>>> >>> >>> The new conditional test needs to be inverted. Try this instead: >>> >>> Index: powerpc/aim/mmu_oea64.c >>> =================================================================== >>> --- powerpc/aim/mmu_oea64.c (revision 269127) >>> +++ powerpc/aim/mmu_oea64.c (working copy) >>> @@ -2274,7 +2274,8 @@ moea64_pvo_enter(mmu_t mmu, pmap_t pm, uma_zone_t >>> if (pvo->pvo_pmap == pm && PVO_VADDR(pvo) == va) { >>> if ((pvo->pvo_pte.lpte.pte_lo & LPTE_RPGN) >>> == pa && >>> (pvo->pvo_pte.lpte.pte_lo & (LPTE_NOEXEC | >>> LPTE_PP)) >>> - == (pte_lo & (LPTE_NOEXEC | LPTE_PP))) { >>> + == (pte_lo & (LPTE_NOEXEC | LPTE_PP)) && >>> + ((pvo->pvo_vaddr ^ flags) & PVO_WIRED) == >>> 0) { >>> if (!(pvo->pvo_pte.lpte.pte_hi & >>> LPTE_VALID)) { >>> /* Re-insert if spilled */ >>> i = MOEA64_PTE_INSERT(mmu, >>> ptegidx, >>> >> >> >> The panic stays, but the message is different: >> >> panic: moea64_pvo_to_pte: pvo 0x10147ea0 has invalid pte 0xb341180 in >> moea64_pteg_table but valid in pvo. >> > > My attempted fix is doing something else wrong. Do you have a stack trace? iPhone sei Dank: http://people.freebsd.org/~andreast/r269134-1_panic.jpg Thanks! Andreas
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