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From: Naoya Horiguchi To: ville.syrjala@linux.intel.com Cc: linux-mm@kvack.org, Andrew Morton , David Hildenbrand , Mike Kravetz , Miaohe Lin , Liu Shixin , Yang Shi , Oscar Salvador , Muchun Song , linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, regressions@lists.linux.dev, naoya.horiguchi@nec.com Subject: Re: [mm-unstable PATCH v7 2/8] mm/hugetlb: make pud_huge() and follow_huge_pud() aware of non-present pud entry Message-ID: <20221104155930.GA527246@ik1-406-35019.vs.sakura.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Migadu-Flow: FLOW_OUT ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667577581; a=rsa-sha256; cv=none; b=t0tt+Ua7OrpzYEwiKB9J90RlKoiwf3s5BneDTcC/LgDzp2/Yf8dwkS5AjRX5pesUUlfSvZ OZo/qeuC7X7utC8XIV4etCVFAmC7MYRnHVb5C3TVAyfqqEADyXjcfTWXj1Gm+QVedOBbzQ urYiOHtZRST3uKlmVF/RvwW81MJPGrg= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=eHtc8Pgj; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf28.hostedemail.com: domain of naoya.horiguchi@linux.dev designates 94.23.1.103 as permitted sender) smtp.mailfrom=naoya.horiguchi@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667577581; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:dkim-signature; bh=hvKqqCFa2Y3MaM+wraMd6xMk0p5uNFUgrkQpd1dibAI=; b=hVUj+E4ol4mZ6RHNJsIrmcZ7Rwsn/ps0QX6H5R+KFDWdHNiZVFZDkTVvQqFEHwUgKFawTH 8JunQjLZwSrMFXOIh45s1Hxshrk/uym96vJlNnP0FofID0QAd2ZIm1fe02xHA/T3P75Ecu DIzc8gKhHWkgjUmXJRJLBhozLs2j6iQ= X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 38DADC0009 X-Rspam-User: Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=eHtc8Pgj; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf28.hostedemail.com: domain of naoya.horiguchi@linux.dev designates 94.23.1.103 as permitted sender) smtp.mailfrom=naoya.horiguchi@linux.dev X-Stat-Signature: bx7wjmm1yqbfn3mn81fmmiqp75rhn9b4 X-HE-Tag: 1667577580-769208 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Nov 02, 2022 at 10:51:40PM +0200, Ville Syrjälä wrote: > On Thu, Jul 14, 2022 at 01:24:14PM +0900, Naoya Horiguchi wrote: > > +/* > > + * pud_huge() returns 1 if @pud is hugetlb related entry, that is normal > > + * hugetlb entry or non-present (migration or hwpoisoned) hugetlb entry. > > + * Otherwise, returns 0. > > + */ > > int pud_huge(pud_t pud) > > { > > - return !!(pud_val(pud) & _PAGE_PSE); > > + return !pud_none(pud) && > > + (pud_val(pud) & (_PAGE_PRESENT|_PAGE_PSE)) != _PAGE_PRESENT; > > } > > Hi, > > This causes i915 to trip a BUG_ON() on x86-32 when I start X. Hello, Thank you for finding and reporting the issue. x86-32 does not enable CONFIG_ARCH_HAS_GIGANTIC_PAGE, so pud_huge() is supposed to be false on x86-32. Doing like below looks to me a fix (reverting to the original behavior for x86-32): diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c index 6b3033845c6d..bf73f25aaa32 100644 --- a/arch/x86/mm/hugetlbpage.c +++ b/arch/x86/mm/hugetlbpage.c @@ -37,8 +37,12 @@ int pmd_huge(pmd_t pmd) */ int pud_huge(pud_t pud) { +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE return !pud_none(pud) && (pud_val(pud) & (_PAGE_PRESENT|_PAGE_PSE)) != _PAGE_PRESENT; +#else + return !!(pud_val(pud) & _PAGE_PSE); // or "return 0;" ? +#endif } #ifdef CONFIG_HUGETLB_PAGE Let me guess what the PUD entry was there when triggering the issue. Assuming that the original code (before 3a194f3f8ad0) was correct, the PSE bit in pud_val(pud) should be always cleared. So, when pud_huge() returns true since 3a194f3f8ad0, the PRESENT bit should be clear and some other bits (rather than PRESENT and PSE) are set so that pud_none() is false. I'm not sure what such a non-present PUD entry does mean. Thanks, Naoya Horiguchi > > [ 225.777375] kernel BUG at mm/memory.c:2664! > [ 225.777391] invalid opcode: 0000 [#1] PREEMPT SMP > [ 225.777405] CPU: 0 PID: 2402 Comm: Xorg Not tainted 6.1.0-rc3-bdg+ #86 > [ 225.777415] Hardware name: /8I865G775-G, BIOS F1 08/29/2006 > [ 225.777421] EIP: __apply_to_page_range+0x24d/0x31c > [ 225.777437] Code: ff ff 8b 55 e8 8b 45 cc e8 0a 11 ec ff 89 d8 83 c4 28 5b 5e 5f 5d c3 81 7d e0 a0 ef 96 c1 74 ad 8b 45 d0 e8 2d 83 49 00 eb a3 <0f> 0b 25 00 f0 ff ff 81 eb 00 00 00 40 01 c3 8b 45 ec 8b 00 e8 76 > [ 225.777446] EAX: 00000001 EBX: c53a3b58 ECX: b5c00000 EDX: c258aa00 > [ 225.777454] ESI: b5c00000 EDI: b5900000 EBP: c4b0fdb4 ESP: c4b0fd80 > [ 225.777462] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 EFLAGS: 00010202 > [ 225.777470] CR0: 80050033 CR2: b5900000 CR3: 053a3000 CR4: 000006d0 > [ 225.777479] Call Trace: > [ 225.777486] ? i915_memcpy_init_early+0x63/0x63 [i915] > [ 225.777684] apply_to_page_range+0x21/0x27 > [ 225.777694] ? i915_memcpy_init_early+0x63/0x63 [i915] > [ 225.777870] remap_io_mapping+0x49/0x75 [i915] > [ 225.778046] ? i915_memcpy_init_early+0x63/0x63 [i915] > [ 225.778220] ? mutex_unlock+0xb/0xd > [ 225.778231] ? i915_vma_pin_fence+0x6d/0xf7 [i915] > [ 225.778420] vm_fault_gtt+0x2a9/0x8f1 [i915] > [ 225.778644] ? lock_is_held_type+0x56/0xe7 > [ 225.778655] ? lock_is_held_type+0x7a/0xe7 > [ 225.778663] ? 0xc1000000 > [ 225.778670] __do_fault+0x21/0x6a > [ 225.778679] handle_mm_fault+0x708/0xb21 > [ 225.778686] ? mt_find+0x21e/0x5ae > [ 225.778696] exc_page_fault+0x185/0x705 > [ 225.778704] ? doublefault_shim+0x127/0x127 > [ 225.778715] handle_exception+0x130/0x130 > [ 225.778723] EIP: 0xb700468a > [ 225.778730] Code: 44 24 40 8b 7c 24 1c 89 47 54 8b 44 24 5c 65 2b 05 14 00 00 00 0f 85 8a 01 00 00 83 c4 6c 5b 5e 5f 5d c3 8b 44 24 1c 8b 40 28 00 00 00 00 00 8b 44 24 20 8d 90 20 1b 00 00 8b 02 83 e8 01 89 > [ 225.778738] EAX: b5900000 EBX: b7148000 ECX: 00000000 EDX: 00000000 > [ 225.778745] ESI: 0103eb60 EDI: b7148000 EBP: b6cf7000 ESP: bfd76650 > [ 225.778752] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b EFLAGS: 00010246 > [ 225.778761] ? doublefault_shim+0x127/0x127 > [ 225.778769] Modules linked in: i915 prime_numbers i2c_algo_bit iosf_mbi drm_buddy video wmi drm_display_helper drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm drm_panel_orientation_quirks backlight cfg80211 rfkill sch_fq_codel xt_tcpudp xt_multiport xt_state iptable_filter iptable_nat nf_nat nf_conntrack nf_defrag_ipv4 ip_tables x_tables binfmt_misc i2c_dev iTCO_wdt snd_intel8x0 snd_ac97_codec ac97_bus snd_pcm snd_timer psmouse i2c_i801 snd i2c_smbus uhci_hcd i2c_core pcspkr soundcore lpc_ich mfd_core ehci_pci ehci_hcd skge intel_agp intel_gtt usbcore agpgart usb_common rng_core parport_pc parport evdev > [ 225.778899] ---[ end trace 0000000000000000 ]--- > [ 225.778906] EIP: __apply_to_page_range+0x24d/0x31c > [ 225.778916] Code: ff ff 8b 55 e8 8b 45 cc e8 0a 11 ec ff 89 d8 83 c4 28 5b 5e 5f 5d c3 81 7d e0 a0 ef 96 c1 74 ad 8b 45 d0 e8 2d 83 49 00 eb a3 <0f> 0b 25 00 f0 ff ff 81 eb 00 00 00 40 01 c3 8b 45 ec 8b 00 e8 76 > [ 225.778924] EAX: 00000001 EBX: c53a3b58 ECX: b5c00000 EDX: c258aa00 > [ 225.778931] ESI: b5c00000 EDI: b5900000 EBP: c4b0fdb4 ESP: c4b0fd80 > [ 225.778938] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 EFLAGS: 00010202 > [ 225.778946] CR0: 80050033 CR2: b5900000 CR3: 053a3000 CR4: 000006d0 > > -- > Ville Syrjälä > Intel