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rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v3 3/3] mm: Batch-zap large anonymous folio PTE mappings To: Nathan Chancellor Cc: Andrew Morton , Matthew Wilcox , Yin Fengwei , David Hildenbrand , Yu Zhao , Yang Shi , "Huang, Ying" , Zi Yan , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20230720112955.643283-1-ryan.roberts@arm.com> <20230720112955.643283-4-ryan.roberts@arm.com> <20230726161942.GA1123863@dev-arch.thelio-3990X> <44a91c46-08ba-9693-6c9c-a0a59921e9f1@arm.com> <20230726195029.GA123524@dev-arch.thelio-3990X> From: Ryan Roberts In-Reply-To: <20230726195029.GA123524@dev-arch.thelio-3990X> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 5C860140004 X-Stat-Signature: asxxd8qny17c91ktzhc3itofbp4sff6a X-Rspam-User: X-HE-Tag: 1690406242-174086 X-HE-Meta: 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 mLeszV5h B8M8Ofh7ptwefNuPUE+rCz92GQ2rNb3GSCB4KTOq4FKmD/uduwEH9LPuYFwQjuC2ABjZLTP6HrKH2lhaznHYUcQP43y7iaelJ4DY/zoT463+SRqA2shKUq9yITgVJqS7Jo55Zs81mtin0auTJC9zg75p3rFUgHLPykEEkoGg8ezgETt5DXjJwhoWC21ISihdYtebz 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 26/07/2023 20:50, Nathan Chancellor wrote: > On Wed, Jul 26, 2023 at 08:38:25PM +0100, Ryan Roberts wrote: >> On 26/07/2023 17:19, Nathan Chancellor wrote: >>> Hi Ryan, >>> >>> On Thu, Jul 20, 2023 at 12:29:55PM +0100, Ryan Roberts wrote: >> >> ... >> >>>> >>> >>> After this change in -next as commit 904d9713b3b0 ("mm: batch-zap large >>> anonymous folio PTE mappings"), I see the following splats several times >>> when booting Debian's s390x configuration (which I have mirrored at [1]) >>> in QEMU (bisect log below): >>> >>> $ qemu-system-s390x \ >>> -display none \ >>> -nodefaults \ >>> -M s390-ccw-virtio \ >>> -kernel arch/s390/boot/bzImage \ >>> -initrd rootfs.cpio \ >>> -m 512m \ >>> -serial mon:stdio >> >> I'm compiling the kernel for next-20230726 using the s390 cross compiler from kernel.org and the config you linked. Then booting with qemu-system-s390x (tried both distro's 4.2.1 and locally built 8.0.3) and the initrd you provided (tried passing it compressed and uncompressed), but I'm always getting a kernel panic due to not finding a rootfs: >> >> $ qemu-system-s390x \ >> -display none \ >> -nodefaults \ >> -M s390-ccw-virtio \ >> -kernel arch/s390/boot/bzImage >> -initrd ../s390-rootfs.cpio.zst \ >> -m 512m \ >> -serial mon:stdio >> KASLR disabled: CPU has no PRNG >> KASLR disabled: CPU has no PRNG >> Linux version 6.5.0-rc3-next-20230726 (ryarob01@e125769) (s390-linux-gcc (GCC) 13.1.0, GNU ld (GNU Binutils) 2.40) #1 SMP Wed Jul 26 19:56:26 BST 2023 >> setup: Linux is running under KVM in 64-bit mode >> setup: The maximum memory size is 512MB >> setup: Relocating AMODE31 section of size 0x00003000 >> cpu: 1 configured CPUs, 0 standby CPUs >> Write protected kernel read-only data: 4036k >> Zone ranges: >> DMA [mem 0x0000000000000000-0x000000007fffffff] >> Normal empty >> Movable zone start for each node >> Early memory node ranges >> node 0: [mem 0x0000000000000000-0x000000001fffffff] >> Initmem setup node 0 [mem 0x0000000000000000-0x000000001fffffff] >> percpu: Embedded 14 pages/cpu s26368 r0 d30976 u57344 >> Kernel command line: >> random: crng init done >> Dentry cache hash table entries: 65536 (order: 7, 524288 bytes, linear) >> Inode-cache hash table entries: 32768 (order: 6, 262144 bytes, linear) >> Built 1 zonelists, mobility grouping on. Total pages: 129024 >> mem auto-init: stack:all(zero), heap alloc:off, heap free:off >> Memory: 507720K/524288K available (3464K kernel code, 788K rwdata, 572K rodata, 796K init, 400K bss, 16568K reserved, 0K cma-reserved) >> SLUB: HWalign=256, Order=0-3, MinObjects=0, CPUs=1, Nodes=1 >> rcu: Hierarchical RCU implementation. >> rcu: RCU restricting CPUs from NR_CPUS=64 to nr_cpu_ids=1. >> rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies. >> rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1 >> NR_IRQS: 3, nr_irqs: 3, preallocated irqs: 3 >> rcu: srcu_init: Setting srcu_struct sizes based on contention. >> clocksource: tod: mask: 0xffffffffffffffff max_cycles: 0x3b0a9be803b0a9, max_idle_ns: 1805497147909793 ns >> Console: colour dummy device 80x25 >> printk: console [ttysclp0] enabled >> pid_max: default: 32768 minimum: 301 >> Mount-cache hash table entries: 1024 (order: 1, 8192 bytes, linear) >> Mountpoint-cache hash table entries: 1024 (order: 1, 8192 bytes, linear) >> rcu: Hierarchical SRCU implementation. >> rcu: Max phase no-delay instances is 1000. >> smp: Bringing up secondary CPUs ... >> smp: Brought up 1 node, 1 CPU >> clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns >> futex hash table entries: 256 (order: 4, 65536 bytes, linear) >> kvm-s390: SIE is not available >> hypfs: The hardware system does not support hypfs >> workingset: timestamp_bits=62 max_order=17 bucket_order=0 >> io scheduler mq-deadline registered >> io scheduler kyber registered >> cio: Channel measurement facility initialized using format extended (mode autodetected) >> Discipline DIAG cannot be used without z/VM >> vmur: The z/VM virtual unit record device driver cannot be loaded without z/VM >> sclp_sd: Store Data request failed (eq=2, di=3, response=0x40f0, flags=0x00, status=0, rc=-5) >> List of all partitions: >> No filesystem could mount root, tried: >> >> Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(1,0) >> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.5.0-rc3-next-20230726 #1 >> Hardware name: QEMU 8561 QEMU (KVM/Linux) >> Call Trace: >> [<0000000000432b22>] dump_stack_lvl+0x62/0x80 >> [<0000000000158898>] panic+0x2f8/0x310 >> [<00000000005b7a56>] mount_root_generic+0x276/0x3b8 >> [<00000000005b7e46>] prepare_namespace+0x56/0x220 >> [<00000000004593e8>] kernel_init+0x28/0x1c8 >> [<000000000010217e>] __ret_from_fork+0x36/0x50 >> [<000000000046143a>] ret_from_fork+0xa/0x30 >> >> >> Any idea what I'm doing wrong here? Do I need to specify something on the kernel command line? (I've tried root=/dev/ram0, but get the same result). > > Hmmm, interesting. The rootfs does need to be used decompressed (I think > the kernel does support zstd compressed initrds but we only compress > them to save space, not for running). Does the sha256sum sum match the > one I just tested? > > $ curl -LSsO https://github.com/ClangBuiltLinux/boot-utils/releases/download/20230707-182910/s390-rootfs.cpio.zst > $ zstd -d s390-rootfs.cpio.zst > $ sha256sum s390-rootfs.cpio > 948fb3c2ad65e26aee8eb0a069f5c9e1ab2c59e4b4f62b63ead271e12a8479b4 s390-rootfs.cpio Yes, this matches. > $ qemu-system-s390x -display none -nodefaults -M s390-ccw-virtio -kernel arch/s390/boot/bzImage -initrd s390-rootfs.cpio -m 512m -serial mon:stdio > ... > [ 7.890385] Trying to unpack rootfs image as initramfs... > ... > > I suppose it could be something with Kconfig too, here is the actual one > that olddefconfig produces for me: > > https://gist.github.com/nathanchance/3e4c1721ac204bbb969e2f288e1695c9 Ahh, I think this was the problem, after downloading this, the kernel is taking much longer to compile and eventually giving me an assembler error: arch/s390/kernel/mcount.S: Assembler messages: arch/s390/kernel/mcount.S:140: Error: Unrecognized opcode: `aghik' make[4]: *** [scripts/Makefile.build:360: arch/s390/kernel/mcount.o] Error 1 make[4]: *** Waiting for unfinished jobs.... make[3]: *** [scripts/Makefile.build:480: arch/s390/kernel] Error 2 make[2]: *** [scripts/Makefile.build:480: arch/s390] Error 2 make[2]: *** Waiting for unfinished jobs.... make[1]: *** [/data_nvme0n1/ryarob01/granule_perf/linux/Makefile:2035: .] Error 2 make: *** [Makefile:234: __sub-make] Error 2 The assembler that comes with the kernel.org toolchain is from binutils 2.40. Perhaps that's too old for this instruction? It's inside an "#ifdef CONFIG_FUNCTION_GRAPH_TRACER" block, so I'm guessing whatever config I was previously using didn't have that enabled. I'll try to disable some configs to workaround. What assembler are you using? > > Cheers, > Nathan