Messages in this thread | | | From | Kamal Dasu <> | Date | Wed, 7 Dec 2022 13:31:19 -0500 | Subject | Re: Invalid pstore_blk use? |
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+ Adrain Hunter + Ulf Hansoon
On Fri, Nov 18, 2022 at 3:41 PM Kamal Dasu <kdasu.kdev@gmail.com> wrote: > > Kees, > > I am in the process of implementing mmcpstore backend for mmc based > on the mtdpstore driver > > This is what is registered with register_pstore_device(&cxt->dev); > cxt->dev.flags = PSTORE_FLAGS_DMESG; > cxt->dev.zone.read = mmcpstore_read; > cxt->dev.zone.write = mmcpstore_write; > cxt->dev.zone.erase = mmcpstore_erase; > cxt->dev.zone.panic_write = mmcpstore_panic_write; > > # dmesg | grep pstor > [ 0.000000] Kernel command line: pstore_blk.blkdev=/dev/mmcblk1p8 > crash_kexec_post_notifiers printk.always_kmsg_dump > [ 1.993986] pstore_zone: registered pstore_blk as backend for > kmsg(Oops,panic_write) pmsg > [ 2.002582] pstore: Using crash dump compression: deflate > [ 2.008133] pstore: Registered pstore_blk as persistent store backend > [ 2.020907] mmcpstore: /dev/mmcblk1p8 size 131072 start sector > 34468 registered as psblk backend > [ 17.868753] psz_kmsg_recover_meta: pstore_zone: no valid data in > kmsg dump zone 0 > [ 18.298933] psz_recover_zone: pstore_zone: no valid data in zone pmsg > [ 18.305398] psz_recovery: pstore_zone: recover end! > > The driver is successfully registered and the read path works when > /sys/fs/pstor is mounted , however mmc_pstore_panic_write is not > called. > Need help in understanding what could be missing. I am using the > latest upstream kernel for testing. > > Kamal > > On Tue, Aug 9, 2022 at 7:06 PM Kees Cook <keescook@chromium.org> wrote: > > > > On Tue, Aug 09, 2022 at 11:35:08AM -0700, Florian Fainelli wrote: > > > Hi Kees, WeiXiong, > > > > > > On 7/14/22 20:49, Florian Fainelli wrote: > > > > Hi Kees, WeiXiong, > > > > > > > > I am trying to make use of pstore_blk which is BTW exactly what I had > > > > been looking for to store panic/console logs onto an eMMC partition. > > > > > > > > Using the 5.10 kernel plus: > > > > > > > > 7e2e92e9861b Revert "mark pstore-blk as broken" > > > > 01c28bc8f389 pstore/blk: Use the normal block device I/O path > > > > 2a7507999638 pstore/blk: remove {un,}register_pstore_blk > > > > fef0b337cd25 pstore/zone: cap the maximum device size > > > > > > > > or the android13-5.15 (at Merge 5.15.40 into android13-5.15) kernel with > > > > no changes and using: > > > > > > > > mount -t pstore pstore /sys/fs/pstore > > > > modprobe pstore_blk blkdev=/dev/mmcblk1p9 best_effort=yes > > > > > > > > upon triggering a crash with: > > > > > > > > echo c > /proc/sysrq-trigger > > > > > > > > and rebooting and remounting the pstore filesystem and loading > > > > pstore_blk, I only have: > > > > > > > > # ls /sys/fs/pstore/ > > > > console-pstore_blk-0 > > > > > > > > which contains the entire console log up to, but excluding the crash. > > > > The kernel does show that pstore_blk was used for all 3 types of kmsg, > > > > pmsg and console: > > > > > > > > [ 28.649514] pstore_zone: capping size to 128MiB > > > > [ 28.712894] pstore_zone: registered pstore_blk as backend for > > > > kmsg(Oops) pmsg console > > > > [ 28.721145] pstore: Using crash dump compression: deflate > > > > [ 28.906253] printk: console [pstore_blk-1] enabled > > > > [ 28.911229] pstore: Registered pstore_blk as persistent store backend > > > > [ 28.917735] pstore_blk: attached pstore_blk:/dev/mmcblk1p9 > > > > (134217728) (no dedicated panic_write!) > > > > > > > > there is no automatic reboot upon panic, so I just tend to reboot after > > > > 2-3 seconds manually. The kernel is configured with the default > > > > CONFIG_PSTORE_* options. > > > > > > > > Is the observed behavior a limitation of the best_effort mode? If so, do > > > > we have any plans to implementing a non-best effort mode for eMMC > > > > devices? > > > > > > Any feedback on my email? I did try to get kernel panics to be dumped out to > > > > Hi! Sorry I lost this email originally. :) > > > > > a dedicated /dev/mtdblock* partition for which there ought to be support for > > > mtd->panic_write, but it still did not work any better. Is there something > > > > With the mtdblock driver, do you still see: > > > > pstore_blk: attached pstore_blk:/dev/... (no dedicated panic_write!) > > ^^^^^^^^^^^^^^^^^^^^^^^^^ > > > > > obvious that I am missing which prevents kernel panics from being logged? > > > > Unfortunately it really depends on how the drivers are built. If the > > block layer is shut down during a panic, pstore_blk won't catch the > > panic. :( > > > > -- > > Kees Cook
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