On Sat, Mar 11, 2017 at 01:01:11PM -0800, Jaegeuk Kim wrote:
> On 03/10, Philippe De Muyter wrote:
> > On Fri, Mar 10, 2017 at 10:20:34AM -0800, Jaegeuk Kim wrote:
> > > On 03/10, Philippe De Muyter wrote:
> > > ...
> > > > > > It is actually a Freescale (now NXP) provided kernel tagged
> > > > > > rel_imx_4.1.15_1.2.0_ga
> > > > > > available at git://git.freescale.com/imx/linux-2.6-imx.git
> > > > > >
> > > > > > I surmise that the f2fs driver is the one from the linux-4.1
> > > > > > version.
> > > > > >
> > > > > > >
> > > > > > > You can get the latest f2fs-tools from
> > > > > > > http://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs-tools.git/log/?h=dev-test
> > > > > > >
> > > > > > > Anyway, if you don't have time, you may have some options like:
> > > > > > >
> > > > > > > 1. disable F2FS_CHECK_FS in Kconfig
> > > > > > > : bypass BUG_ON here, so mount-ro would be preferable.
> > > > > >
> > > > > > Actually F2FS_CHECK_FS was disabled, but kernel panic'ed.
> > > > >
> > > > > So, you got a warning message from there?
> > > > >
> > > > > #ifdef CONFIG_F2FS_CHECK_FS
> > > > > #define f2fs_bug_on(sbi, condition) BUG_ON(condition)
> > > > > #define f2fs_down_write(x, y) down_write_nest_lock(x, y)
> > > > > #else
> > > > > #define f2fs_bug_on(sbi, condition)
> > > > > \
> > > > > do {
> > > > > \
> > > > > if (unlikely(condition)) {
> > > > > \
> > > > > WARN_ON(1);
> > > > > \
> > > > > set_sbi_flag(sbi, SBI_NEED_FSCK);
> > > > > \
> > > > > }
> > > > > \
> > > > > } while (0)
> > > > > #define f2fs_down_write(x, y) down_write(x)
> > > > > #endif
> > > >
> > > > Yes, I got a 'panic'. I'll look deeper into that and let you know.
> > >
> > > Okay, thank you. ;)
> >
> > For a test, I forced a call to f2fs_bug_on(sbi, 1) at the entry of
> > init_dirty_segmap(),
> > and tested on another board but only got a message, not a panic, so I don't
> > know
> > what happened on the first board. If it happens again on another board,
> > I'll
> > try to collect more info.
>
> BTW, do you have the corrupted image? Then, you can back up it and run fsck to
> retrieve some information on it. Or, can you share?
No unfortunately, the device got reflashed before I had any chance so save
a copy of the partition. If it happens again, I'll save it.
>
> > > > > > > 2. run fsck.f2fs
> > > > > > > : fix some inconsistency and let you mount your system again.
> > > > > > >
> > > > > > > So, I think you'd better try #1 to retrieve your important data,
> > > > > > > and then
> > > > > > > #2 to fix something wrong.
> > > > > >
> > > > > > There wasn't a need to retrieve important data, as it is an
> > > > > > unattended device
> > > > > > in the wild. The problem was that boot did not succeed anymore and
> > > > > > the device
> > > > > > needed a return to our aftersales department for reflashing.
> > > > > > Without the 'panic',
> > > > > > and with a read-only mount we could probably fix it without
> > > > > > reflashing
> > > > > > and without return.
> > > > >
> > > > > So, there is no fscking before mounting any filesystem during
> > > > > boot-up, right?
> > > > > Most of distros and android do that and provide a recovery mode tho.
> > > >
> > > > No, there is no fsck before mounting the root filesystem during boot-up.
> > > > But I do my best to avoid writing in the root partition. It's not
> > > > read-only,
> > > > but all log, lock, run, cache and tmp files are in tmpfs partitions. I
> > > > have
> > > > just noticed though that the partition is mounted with 'relatime', not
> > > > 'noatime'
> > > > as I would like, but I do not know where this 'relatime' option comes
> > > > from.
> > > > Is 'relatime' a default mount option for f2fs ?
> > >
> > > Not specific from f2fs. It's default given by vfs, and you need to mount
> > > with
> > > noatime explicitly, if you want. BTW, once you got a panic during
> > > boot-up, how
> > > can you change mount option?
> >
> > It is a ARM board, started by U-boot. I can change the kernel command-line,
> > and hope the kernel will understand the noatime option.
> >
> > I wasn't speaking about changing the mount option after a panic, but about
> > changing
> > the default mount option on all the new boards, to avoid unvoluntary writes
> > to the
> > eMMC.
>
> If there was almost no change in the root partition, that may happen due to
> other reason like overwritting block device by user accidently.
> (fsck can show some clues tho.)
I am aware of two possible external causes
- some dma engine on my device does not always terminate when the user process
using it terminates and the memory is freed :( (a GPU or VPU with hidden
firmware)
- there is no UPS to power the device and hence the eMMC
Therefor I really prefer to have 'noatime' rather than 'relatime' set.
I now found that specifying "rootflags=noatime" on the linux command-line does
not
work for the root partition, as it answers :
Unrecognized mount option "noatime" or missing value
I also saw in linux sources that 'jffs2' sets arbitrarily 'noatime'. I'll try
to
do the same for f2fs.
>
> Thanks,
>
> >
> > >
> > > Thanks,
> > >
> > > >
> > > > >
> > > > > I think there is a way to mount with ro without loading in-memory
> > > > > structures
> > > > > which results in potential panics. Will cosider about that. ;)
> > > > >
> > > > > Note, there is a backported f2fs for v4.1 which I've been maintaining.
> > > > >
> > > > > http://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs-stable.git/log/?h=linux-4.1.y
> > > >
> > > > Thank you. I will apply it
> > > >
> > > > Philippe
--
Philippe De Muyter +32 2 6101532 Macq SA rue de l'Aeronef 2 B-1140 Bruxelles
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