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[2a03:2880:12ff:73::face:b00c]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-5e3b0d94409sm3611397eaf.18.2024.09.23.11.34.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Sep 2024 11:34:59 -0700 (PDT) From: Manu Bretelle To: dhowells@redhat.com Cc: asmadeus@codewreck.org, ceph-devel@vger.kernel.org, christian@brauner.io, ericvh@kernel.org, hsiangkao@linux.alibaba.com, idryomov@gmail.com, jlayton@kernel.org, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-nfs@vger.kernel.org, marc.dionne@auristor.com, netdev@vger.kernel.org, netfs@lists.linux.dev, pc@manguebit.com, smfrench@gmail.com, sprasad@microsoft.com, tom@talpey.com, v9fs@lists.linux.dev, willy@infradead.org, eddyz87@gmail.com Subject: [PATCH v2 19/25] netfs: Speed up buffered reading Date: Mon, 23 Sep 2024 11:34:32 -0700 Message-ID: <20240923183432.1876750-1-chantr4@gmail.com> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20240814203850.2240469-20-dhowells@redhat.com> References: <20240814203850.2240469-20-dhowells@redhat.com> Precedence: bulk X-Mailing-List: netfs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi David, It seems this commit (ee4cdf7ba857: "netfs: Speed up buffered reading") broke booting vms using qemu. It still reproduces on top of linux-master. BPF CI has failed to boot kernels with the following trace [0]. Bisect narrowed it down to this commit. Reverting ee4cdf7ba857 on to of current bpf-next master with [1] (basically ee4cdf7ba857 where I had to manually edit some conflict to the best of my uneducated knowledge) gets qemu boot back on track. This can be reproed by following the build steps in [2]. Assuming danobi/vmtest [3] is already installed, here is the script used during bisect. #!/bin/bash cat tools/testing/selftests/bpf/config{,.$(uname -m),.vm} > .config make olddefconfig make -j$((4* $(nproc))) || exit 125 timeout 10 vmtest -k $(make -s image_name) "echo yeah" exit $? The qemu command invoked by vmtest is: qemu-system-x86_64 "-nodefaults" "-display" "none" "-serial" "mon:stdio" \ "-enable-kvm" "-cpu" "host" "-qmp" "unix:/tmp/qmp-971717.sock,server=on,wait=off" \ "-chardev" "socket,path=/tmp/qga-888301.sock,server=on,wait=off,id=qga0" \ "-device" "virtio-serial" \ "-device" "virtserialport,chardev=qga0,name=org.qemu.guest_agent.0" \ "--device" "virtio-serial" \ "-chardev" "socket,path=/tmp/cmdout-508724.sock,server=on,wait=off,id=cmdout" \ "--device" "virtserialport,chardev=cmdout,name=org.qemu.virtio_serial.0" \ "-virtfs" "local,id=root,path=/,mount_tag=/dev/root,security_model=none,multidevs=remap" \ "-kernel" "/data/users/chantra/linux/arch/x86/boot/bzImage" \ "-no-reboot" "-append" "rootfstype=9p rootflags=trans=virtio,cache=mmap,msize=1048576 rw earlyprintk=serial,0,115200 printk.devkmsg=on console=0,115200 loglevel=7 raid=noautodetect init=/tmp/vmtest-init4PdCA.sh panic=-1" \ "-virtfs" "local,id=shared,path=/data/users/chantra/linux,mount_tag=vmtest-shared,security_model=none,multidevs=remap" \ "-smp" "2" "-m" "4G" [0] https://gist.github.com/chantra/683d9d085c28b7971bbc6f76652c22f3 [1] https://gist.github.com/chantra/642868407d10626fd44febdfed0a4fce [2] https://chantra.github.io/bpfcitools/bpf-local-development.html#building-a-vm-friendly-kernel-for-bpf [3] https://github.com/danobi/vmtest