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h=Content-Transfer-Encoding:Content-Type:In-Reply-To: References:Cc:To:From:Subject:MIME-Version:Date:Message-ID; bh=BH1SvWNFn+/0pXsiXRGsXt+pBKip9G+iv18Mri06eEo=; b=mUW/sYbnzfVNUKLHrovqpIIUdF 82jIS6lIPL7u3OXTnd78rmXJ7GHUFMb+y9+WX2WTwFx3xVPBbIeAlBrY9967mQTnm6sMYvVF4Oq/c 1La0uwxJcWbdZdH/ZpRlosfMGyELRpvP9YZeUkFz0xxxvTw6sFZmYqM9wwX4J9hTg2xc=; Message-ID: <9e0f7ff3-5457-41e4-a1e4-bf75804fb900@xen.org> Date: Thu, 21 Mar 2024 16:10:30 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 08/14] xen/page_alloc: introduce preserved page flags macro Content-Language: en-GB From: Julien Grall To: Carlo Nonato , xen-devel@lists.xenproject.org Cc: Andrew Cooper , George Dunlap , Jan Beulich , Stefano Stabellini , Wei Liu , =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= References: <20240315105902.160047-1-carlo.nonato@minervasys.tech> <20240315105902.160047-9-carlo.nonato@minervasys.tech> <3f615066-a792-493f-ba33-7667a6557c23@xen.org> In-Reply-To: <3f615066-a792-493f-ba33-7667a6557c23@xen.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 21/03/2024 16:07, Julien Grall wrote: > (+ Roger) > > Hi Carlo, > > On 15/03/2024 10:58, Carlo Nonato wrote: >> PGC_static and PGC_extra needs to be preserved when assigning a page. >> Define a new macro that groups those flags and use it instead of or'ing >> every time. >> >> To make preserved flags even more meaningful, they are kept also when >> switching state in mark_page_free(). >> >> Signed-off-by: Carlo Nonato > > This patch is introducing a regression in OSStest (and possibly gitlab?): > > Mar 21 12:00:29.533676 (XEN) pg[0] MFN 2211c5 c=0x2c00000000000000 o=0 > v=0xe40000010007ffff t=0x24 > Mar 21 12:00:42.829785 (XEN) Xen BUG at common/page_alloc.c:1033 > Mar 21 12:00:42.829829 (XEN) ----[ Xen-4.19-unstable  x86_64  debug=y > Not tainted ]---- > Mar 21 12:00:42.829857 (XEN) CPU:    12 > Mar 21 12:00:42.841571 (XEN) RIP:    e008:[] > common/page_alloc.c#alloc_heap_pages+0x37f/0x6e2 > Mar 21 12:00:42.841609 (XEN) RFLAGS: 0000000000010282   CONTEXT: > hypervisor (d0v8) > Mar 21 12:00:42.853654 (XEN) rax: ffff83023e3ed06c   rbx: > 000000000007ffff   rcx: 0000000000000028 > Mar 21 12:00:42.853689 (XEN) rdx: ffff83047bec7fff   rsi: > ffff83023e3ea3e8   rdi: ffff83023e3ea3e0 > Mar 21 12:00:42.865657 (XEN) rbp: ffff83047bec7c10   rsp: > ffff83047bec7b98   r8:  0000000000000000 > Mar 21 12:00:42.877647 (XEN) r9:  0000000000000001   r10: > 000000000000000c   r11: 0000000000000010 > Mar 21 12:00:42.877682 (XEN) r12: 0000000000000001   r13: > 0000000000000000   r14: ffff82e0044238a0 > Mar 21 12:00:42.889652 (XEN) r15: 0000000000000000   cr0: > 0000000080050033   cr4: 0000000000372660 > Mar 21 12:00:42.901651 (XEN) cr3: 000000046fe34000   cr2: 00007fb72757610b > Mar 21 12:00:42.901685 (XEN) fsb: 00007fb726def380   gsb: > ffff88801f200000   gss: 0000000000000000 > Mar 21 12:00:42.913646 (XEN) ds: 0000   es: 0000   fs: 0000   gs: 0000 > ss: e010   cs: e008 > Mar 21 12:00:42.913680 (XEN) Xen code around > (common/page_alloc.c#alloc_heap_pages+0x37f/0x6e2): > Mar 21 12:00:42.925645 (XEN)  d1 1c 00 e8 ad dd 02 00 <0f> 0b 48 85 c9 > 79 36 0f 0b 41 89 cd 48 c7 47 f0 > Mar 21 12:00:42.937649 (XEN) Xen stack trace from rsp=ffff83047bec7b98: > Mar 21 12:00:42.937683 (XEN)    0000000000000024 000000007bec7c20 > 0000000000000001 ffff83046ccda000 > Mar 21 12:00:42.949653 (XEN)    ffff82e000000021 0000000000000016 > 0000000000000000 0000000000000000 > Mar 21 12:00:42.949687 (XEN)    0000000000000000 0000000000000000 > 0000000000000028 0000000000000021 > Mar 21 12:00:42.961652 (XEN)    ffff83046ccda000 0000000000000000 > 00007d2000000000 ffff83047bec7c48 > Mar 21 12:00:42.961687 (XEN)    ffff82d0402302ff ffff83046ccda000 > 0000000000000100 0000000000000000 > Mar 21 12:00:42.973655 (XEN)    ffff82d0405f0080 00007d2000000000 > ffff83047bec7c80 ffff82d0402f626c > Mar 21 12:00:42.985656 (XEN)    ffff83046ccda000 ffff83046ccda640 > 0000000000000000 0000000000000000 > Mar 21 12:00:42.985690 (XEN)    ffff83046ccda220 ffff83047bec7cb0 > ffff82d0402f65a0 ffff83046ccda000 > Mar 21 12:00:42.997662 (XEN)    0000000000000000 0000000000000000 > 0000000000000000 ffff83047bec7cc0 > Mar 21 12:00:43.009660 (XEN)    ffff82d040311f8a ffff83047bec7ce0 > ffff82d0402bd543 ffff83046ccda000 > Mar 21 12:00:43.009695 (XEN)    ffff83047bec7dc8 ffff83047bec7d08 > ffff82d04032c524 ffff83046ccda000 > Mar 21 12:00:43.021653 (XEN)    ffff83047bec7dc8 0000000000000002 > ffff83047bec7d58 ffff82d040206750 > Mar 21 12:00:43.033642 (XEN)    0000000000000000 ffff82d040233fe5 > ffff83047bec7d48 0000000000000000 > Mar 21 12:00:43.033678 (XEN)    0000000000000002 00007fb72767f010 > ffff82d0405e9120 0000000000000001 > Mar 21 12:00:43.045654 (XEN)    ffff83047bec7e70 ffff82d040240728 > 0000000000000007 ffff83023e3b3000 > Mar 21 12:00:43.045690 (XEN)    0000000000000246 ffff83023e2efa90 > ffff83023e38e000 ffff83023e2efb40 > Mar 21 12:00:43.057609 (XEN)    0000000000000007 ffff83023e3afb80 > 0000000000000206 ffff83047bec7dc0 > Mar 21 12:00:43.069662 (XEN)    0000001600000001 000000000000ffff > e75aaa8d0000000c ac0d6d864e487f62 > Mar 21 12:00:43.069697 (XEN)    000000037fa48d76 0000000200000000 > ffffffff000003ff 00000002ffffffff > Mar 21 12:00:43.081647 (XEN)    0000000000000000 00000000000001ff > 0000000000000000 0000000000000000 > Mar 21 12:00:43.093646 (XEN) Xen call trace: > Mar 21 12:00:43.093677 (XEN)    [] R > common/page_alloc.c#alloc_heap_pages+0x37f/0x6e2 > Mar 21 12:00:43.093705 (XEN)    [] F > alloc_domheap_pages+0x17d/0x1e4 > Mar 21 12:00:43.105652 (XEN)    [] F > hap_set_allocation+0x73/0x23c > Mar 21 12:00:43.105685 (XEN)    [] F > hap_enable+0x138/0x33c > Mar 21 12:00:43.117646 (XEN)    [] F > paging_enable+0x2d/0x45 > Mar 21 12:00:43.117679 (XEN)    [] F > hvm_domain_initialise+0x185/0x428 > Mar 21 12:00:43.129652 (XEN)    [] F > arch_domain_create+0x3e7/0x4c1 > Mar 21 12:00:43.129687 (XEN)    [] F > domain_create+0x4cc/0x7e2 > Mar 21 12:00:43.141665 (XEN)    [] F > do_domctl+0x1850/0x192d > Mar 21 12:00:43.141699 (XEN)    [] F > pv_hypercall+0x617/0x6b5 > Mar 21 12:00:43.153656 (XEN)    [] F > lstar_enter+0x13a/0x140 > Mar 21 12:00:43.153689 (XEN) > Mar 21 12:00:43.153711 (XEN) > Mar 21 12:00:43.153731 (XEN) **************************************** > Mar 21 12:00:43.165647 (XEN) Panic on CPU 12: > Mar 21 12:00:43.165678 (XEN) Xen BUG at common/page_alloc.c:1033 > Mar 21 12:00:43.165703 (XEN) **************************************** > Mar 21 12:00:43.177633 (XEN) > Mar 21 12:00:43.177662 (XEN) Manual reset required ('noreboot' specified) > > The code around the BUG is: > >         /* Reference count must continuously be zero for free pages. */ >         if ( (pg[i].count_info & ~PGC_need_scrub) != PGC_state_free ) >         { >             printk(XENLOG_ERR >                    "pg[%u] MFN %"PRI_mfn" c=%#lx o=%u v=%#lx t=%#x\n", >                    i, mfn_x(page_to_mfn(pg + i)), >                    pg[i].count_info, pg[i].v.free.order, >                    pg[i].u.free.val, pg[i].tlbflush_timestamp); >             BUG(); >         } > > Now that you are preserving some flags, you also want to modify the > condition. I haven't checked the rest of the code, so there might be > some adjustments necessary. Actually maybe the condition should not be adjusted. I think it would be wrong if a free pages has the flag PGC_extra set. Any thoughts? Cheers, -- Julien Grall