From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3FC28C54E41 for ; Thu, 29 Feb 2024 14:18:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To: Subject:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=lqJ79PX81qrt2yheqM3X5XgxSTi6oK1NCPiwqZpF+O0=; b=GH/WpyvTdu6HBE q9saD9doUFco1QLMkHZoy1U8gkxCav9hMe7pE62FcHFJO9UN0EsrSDmlSjog+aw+QnBMjVfXmay5L SbVzqr0yhBhRCn/aejmUSs0FrUO+pt9OAVa8+7sxZOQiImdzF2qcTBCz907JKtM/R222w195FJeAt tMULJz8H6KA/JraVlOBe/jRnYqzEua8FGlYgLvEeiK08/1aUYRnhXpo+v3zRGUKl8BWWuNACL8lDC C0nwB+YKssIoqHRdmCjCEkGRG+VFZSeH/VnhlEtzfuIlAD3XwMkteY+EEDcZqIY96RsyMP5pUKKL1 f6HURJzbUAoSId3JthnA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rfhEa-0000000Dpi9-0EVr; Thu, 29 Feb 2024 14:18:04 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rfhEX-0000000DphP-3W4T for linux-arm-kernel@lists.infradead.org; Thu, 29 Feb 2024 14:18:03 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5E6C41FB; Thu, 29 Feb 2024 06:18:37 -0800 (PST) Received: from [10.57.68.58] (unknown [10.57.68.58]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D71163F6C4; Thu, 29 Feb 2024 06:17:54 -0800 (PST) Message-ID: Date: Thu, 29 Feb 2024 14:17:52 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 36/43] arm64: mm: Add support for folding PUDs at runtime Content-Language: en-GB To: Ard Biesheuvel , linux-arm-kernel@lists.infradead.org Cc: Ard Biesheuvel , Catalin Marinas , Will Deacon , Marc Zyngier , Mark Rutland , Anshuman Khandual , Kees Cook , Aishwarya TCV , Mark Brown References: <20240214122845.2033971-45-ardb+git@google.com> <20240214122845.2033971-81-ardb+git@google.com> From: Ryan Roberts In-Reply-To: <20240214122845.2033971-81-ardb+git@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240229_061802_001985_D7FC4A70 X-CRM114-Status: GOOD ( 15.82 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Ard, On 14/02/2024 12:29, Ard Biesheuvel wrote: > From: Ard Biesheuvel > > In order to support LPA2 on 16k pages in a way that permits non-LPA2 > systems to run the same kernel image, we have to be able to fall back to > at most 48 bits of virtual addressing. > > Falling back to 48 bits would result in a level 0 with only 2 entries, > which is suboptimal in terms of TLB utilization. So instead, let's fall > back to 47 bits in that case. This means we need to be able to fold PUDs > dynamically, similar to how we fold P4Ds for 48 bit virtual addressing > on LPA2 with 4k pages. I'm seeing a panic during boot in today's linux-next (20240229) and bisect seems pretty confident that this commit is the offender. That said, its the merge commit that shows up as the problem commit: 26843fe8fa72 Merge branch 'for-next/core' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux but when testing the arm64's for-next/core, the problem doesn't exist. So I rebased the branch into linux-next and bisected again. That time, it fingers this patch. So I guess there is some interaction between this and other changes in next? Note I'm running defconfig (so 4K base pages) plus: # Squashfs for snaps, xfs for large file folios. ./scripts/config --enable CONFIG_SQUASHFS_LZ4 ./scripts/config --enable CONFIG_SQUASHFS_LZO ./scripts/config --enable CONFIG_SQUASHFS_XZ ./scripts/config --enable CONFIG_SQUASHFS_ZSTD ./scripts/config --enable CONFIG_XFS_FS # Useful trace features (on for Ubuntu configs). ./scripts/config --enable CONFIG_FTRACE ./scripts/config --enable CONFIG_FUNCTION_TRACER ./scripts/config --enable CONFIG_KPROBES ./scripts/config --enable CONFIG_HIST_TRIGGERS ./scripts/config --enable CONFIG_FTRACE_SYSCALLS # For general mm debug. ./scripts/config --enable CONFIG_DEBUG_VM ./scripts/config --enable CONFIG_DEBUG_VM_MAPLE_TREE ./scripts/config --enable CONFIG_DEBUG_VM_RB ./scripts/config --enable CONFIG_DEBUG_VM_PGFLAGS ./scripts/config --enable CONFIG_DEBUG_VM_PGTABLE ./scripts/config --enable CONFIG_PAGE_TABLE_CHECK # For mm selftests. ./scripts/config --enable CONFIG_USERFAULTFD ./scripts/config --enable CONFIG_TEST_VMALLOC ./scripts/config --enable CONFIG_GUP_TEST # Ram block device for testing swap changes. ./scripts/config --enable CONFIG_BLK_DEV_RAM I'm booting a VM on Apple M2 with 12G RAM assigned, split evenly across 2 emulated numa nodes, and with a bunch of hugetlb pages of all sizes reserved, if that matters. And I see this panic during boot (I guess due to the VM_DEBUG Kconfigs): [ 0.161062] debug_vm_pgtable: [debug_vm_pgtable ]: Validating architecture page table helpers [ 0.161416] BUG: Bad page state in process swapper/0 pfn:18a65d [ 0.161634] page does not match folio [ 0.161753] page: refcount:0 mapcount:-512 mapping:0000000000000000 index:0x0 pfn:0x18a65d [ 0.162046] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008 [ 0.162332] Mem abort info: [ 0.162427] ESR = 0x0000000096000004 [ 0.162559] EC = 0x25: DABT (current EL), IL = 32 bits [ 0.162723] SET = 0, FnV = 0 [ 0.162827] EA = 0, S1PTW = 0 [ 0.162933] FSC = 0x04: level 0 translation fault [ 0.163089] Data abort info: [ 0.163189] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 [ 0.163370] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 [ 0.163539] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 0.163719] [0000000000000008] user address but active_mm is swapper [ 0.163934] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP [ 0.164143] Modules linked in: [ 0.164251] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 6.8.0-rc6-00966-gde701dc1f7f8 #25 [ 0.164516] Hardware name: linux,dummy-virt (DT) [ 0.164704] pstate: 21400005 (nzCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) [ 0.165052] pc : get_pfnblock_flags_mask+0x3c/0x68 [ 0.165281] lr : __dump_page+0x1a0/0x408 [ 0.165504] sp : ffff80008007b8f0 [ 0.165715] x29: ffff80008007b8f0 x28: 0000000000ffffc0 x27: 0000000000000000 [ 0.166047] x26: ffff80008007b950 x25: 0000000000000000 x24: 00000000fffffdff [ 0.166358] x23: ffffba8a417ba000 x22: 000000000018a65d x21: ffffba8a41601bf8 [ 0.166701] x20: ffff80008007b950 x19: ffff80008007b950 x18: 0000000000000006 [ 0.167036] x17: 78303a7865646e69 x16: 2030303030303030 x15: 0720072007200720 [ 0.167365] x14: 0720072007200720 x13: 0720072007200720 x12: 0720072007200720 [ 0.167693] x11: 0720072007200720 x10: ffffba8a4269c038 x9 : ffffba8a3fb0d0b8 [ 0.168017] x8 : 00000000ffffefff x7 : ffffba8a4269c038 x6 : 80000000fffff000 [ 0.168346] x5 : 000003fffff81de4 x4 : 0001fffffc0ef230 x3 : 0000000000000000 [ 0.168699] x2 : 0000000000000007 x1 : fffffe0779181ee5 x0 : 00000000001fffff [ 0.169041] Call trace: [ 0.169164] get_pfnblock_flags_mask+0x3c/0x68 [ 0.169413] dump_page+0x2c/0x70 [ 0.169565] bad_page+0x84/0x130 [ 0.169734] free_page_is_bad_report+0xa0/0xb8 [ 0.169958] free_unref_page_prepare+0x350/0x428 [ 0.170132] free_unref_page+0x50/0x1f0 [ 0.170278] __free_pages+0x11c/0x160 [ 0.170417] free_pages.part.0+0x6c/0x88 [ 0.170576] free_pages+0x1c/0x38 [ 0.170703] destroy_args+0x1c8/0x330 [ 0.170890] debug_vm_pgtable+0xae8/0x10f8 [ 0.171059] do_one_initcall+0x60/0x2c0 [ 0.171222] kernel_init_freeable+0x1ec/0x3d8 [ 0.171406] kernel_init+0x28/0x1f0 [ 0.171557] ret_from_fork+0x10/0x20 [ 0.171712] Code: d37b1884 f100007f 8b040064 9a831083 (f9400460) [ 0.171963] ---[ end trace 0000000000000000 ]--- [ 0.172156] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b [ 0.172383] SMP: stopping secondary CPUs [ 0.172649] Kernel Offset: 0x3a89bf800000 from 0xffff800080000000 [ 0.173923] PHYS_OFFSET: 0xfffff76180000000 [ 0.174585] CPU features: 0x0,00000000,2004454a,13867723 [ 0.175707] Memory Limit: none [ 0.176261] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]--- bisection log (after rebasing arm64 stuff onto linux-next): git bisect start # bad: [446381d9ff3498f7c406109fac88d10bf855d0bd] arm64: Update setup_arch() comment on interrupt masking git bisect bad 446381d9ff3498f7c406109fac88d10bf855d0bd # good: [7f43e0f76e4710b2882c551519eff50e502115c5] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux.git git bisect good 7f43e0f76e4710b2882c551519eff50e502115c5 # good: [36da1bf4c61bf1e4322b9b04d6eb1aba2a515b73] arm64: mm: omit redundant remap of kernel image git bisect good 36da1bf4c61bf1e4322b9b04d6eb1aba2a515b73 # bad: [38f5662b4788b308f3be3cdd15e6c0149a627937] mm: add arch hook to validate mmap() prot flags git bisect bad 38f5662b4788b308f3be3cdd15e6c0149a627937 # good: [653a0b074c33c48913c78e72a000ff935ff208c2] arm64: mm: add LPA2 and 5 level paging support to G-to-nG conversion git bisect good 653a0b074c33c48913c78e72a000ff935ff208c2 # bad: [ebc9452776ee8d978908eb2f7424838b0bff6285] arm64: ptdump: Disregard unaddressable VA space git bisect bad ebc9452776ee8d978908eb2f7424838b0bff6285 # good: [1d8cd0e6257930b0df58ce51bca44e232dcce49c] arm64: mm: Add 5 level paging support to fixmap and swapper handling git bisect good 1d8cd0e6257930b0df58ce51bca44e232dcce49c # bad: [de701dc1f7f88e85aca48e4c76c66f03ac5fc55b] arm64: mm: Add support for folding PUDs at runtime git bisect bad de701dc1f7f88e85aca48e4c76c66f03ac5fc55b # good: [3561c4b14b23f03f109e954b5d89839bb8b73798] arm64: kasan: Reduce minimum shadow alignment and enable 5 level paging git bisect good 3561c4b14b23f03f109e954b5d89839bb8b73798 # first bad commit: [de701dc1f7f88e85aca48e4c76c66f03ac5fc55b] arm64: mm: Add support for folding PUDs at runtime I haven't looked in detail at your patch, but hoped you might get to the root cause quicker than me? Thanks, Ryan _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel