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Subject: Re: [PATCH 16/23] initramfs: simplify clean_rootfs
To:     Christoph Hellwig <hch@lst.de>, linux-kernel@vger.kernel.org
Cc:     "H. Peter Anvin" <hpa@zytor.com>, Song Liu <song@kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-raid@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
From:   Marek Szyprowski <m.szyprowski@samsung.com>
Message-ID: <7f37802c-d8d9-18cd-7394-df51fa785988@samsung.com>
Date:   Fri, 17 Jul 2020 22:55:48 +0200
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References: <20200714190427.4332-1-hch@lst.de>
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Hi Christoph,

On 14.07.2020 21:04, Christoph Hellwig wrote:
> Just use d_genocide instead of iterating through the root directory with
> cumbersome userspace-like APIs.  This also ensures we actually remove files
> that are not direct children of the root entry, which the old code failed
> to do.
>
> Fixes: df52092f3c97 ("fastboot: remove duplicate unpack_to_rootfs()")
> Signed-off-by: Christoph Hellwig <hch@lst.de>

This patch breaks initrd support ;-(

I use initrd to deploy kernel modules on my test machines. It was 
automatically mounted on /initrd. /lib/modules is just a symlink to 
/initrd. I know that initrd support is marked as deprecated, but it 
would be really nice to give people some time to update their machines 
before breaking the stuff.

Here is the log:

Kernel image @ 0x40007fc0 [ 0x000000 - 0x6dd9c8 ]
## Flattened Device Tree blob at 41000000
    Booting using the fdt blob at 0x41000000
    Loading Ramdisk to 4de3c000, end 50000000 ... OK
    Loading Device Tree to 4de2d000, end 4de3b206 ... OK

Starting kernel ...

[    0.000000] Booting Linux on physical CPU 0x900
...

[    0.000000] Kernel command line: root=PARTLABEL=rootfs rootwait 
console=tty1 console=ttySAC2,115200n8 earlycon rootdelay=2
...

[    1.853631] Trying to unpack rootfs image as initramfs...
[    1.858661] rootfs image is not initramfs (invalid magic at start of 
compressed archive); looks like an initrd
...
[    2.204776] Freeing initrd memory: 34576K

...

[    4.635360] Warning: unable to open an initial console.
[    4.640706] Waiting 2 sec before mounting root device...
...
[    6.776007] Failed to create /dev/root: -2
[    6.778989] VFS: Cannot open root device "PARTLABEL=rootfs" or 
unknown-block(179,6): error -2
[    6.787200] Please append a correct "root=" boot option; here are the 
available partitions:
[    6.795693] 0100           65536 ram0
[    6.795697]  (driver?)
[    6.801459] 0101           65536 ram1
[    6.801462]  (driver?)
[    6.807532] 0102           65536 ram2
[    6.807535]  (driver?)
[    6.813674] 0103           65536 ram3
[    6.813677]  (driver?)
[    6.819760] 0104           65536 ram4
[    6.819763]  (driver?)
[    6.832610] 0105           65536 ram5
[    6.832613]  (driver?)
[    6.848685] 0106           65536 ram6
[    6.848688]  (driver?)
[    6.864590] 0107           65536 ram7
[    6.864593]  (driver?)
[    6.880504] 0108           65536 ram8
[    6.880507]  (driver?)
[    6.896248] 0109           65536 ram9
[    6.896251]  (driver?)
[    6.911828] 010a           65536 ram10
[    6.911831]  (driver?)
[    6.927447] 010b           65536 ram11
[    6.927450]  (driver?)
[    6.942976] 010c           65536 ram12
[    6.942979]  (driver?)
[    6.958190] 010d           65536 ram13
[    6.958193]  (driver?)
[    6.973205] 010e           65536 ram14
[    6.973208]  (driver?)
[    6.988105] 010f           65536 ram15
[    6.988108]  (driver?)
[    7.002897] b300        15388672 mmcblk0
[    7.002901]  driver: mmcblk
[    7.018061]   b301            8192 mmcblk0p1 
654b73ea-7c04-c24d-9642-2a186649605c
[    7.018064]
[    7.035359]   b302           61440 mmcblk0p2 
7ef6fb83-0d6c-8c44-826b-ad11df290e0c
[    7.035362]
[    7.052589]   b303          102400 mmcblk0p3 
34883856-7d52-d548-a196-718efbd06876
[    7.052592]
[    7.069744]   b304          153600 mmcblk0p4 
8d4410d0-a4ff-c447-abb9-73350dcdd2d6
[    7.069747]
[    7.086888]   b305         1572864 mmcblk0p5 
485c2c17-a9e8-9c45-bb68-e0748a2bb1f1
[    7.086890]
[    7.103991]   b306         3072000 mmcblk0p6 
7fb2bbf3-e064-2343-b169-e69c18dbb43e
[    7.103993]
[    7.121290]   b307        10413039 mmcblk0p7 
b0ee9150-6b6a-274b-9ec3-703d29072555
[    7.121292]
[    7.138722] Kernel panic - not syncing: VFS: Unable to mount root fs 
on unknown-block(179,6)
[    7.151482] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 
5.8.0-rc5-00064-g38d014f6d446 #8823
[    7.164026] Hardware name: Samsung Exynos (Flattened Device Tree)
[    7.174556] [<c011188c>] (unwind_backtrace) from [<c010d27c>] 
(show_stack+0x10/0x14)
[    7.186799] [<c010d27c>] (show_stack) from [<c05182e4>] 
(dump_stack+0xbc/0xe8)
[    7.198533] [<c05182e4>] (dump_stack) from [<c01272e0>] 
(panic+0x128/0x354)
[    7.210002] [<c01272e0>] (panic) from [<c1001580>] 
(mount_block_root+0x1a8/0x240)
[    7.221961] [<c1001580>] (mount_block_root) from [<c1001738>] 
(mount_root+0x120/0x13c)
[    7.234325] [<c1001738>] (mount_root) from [<c10018ac>] 
(prepare_namespace+0x158/0x194)
[    7.246751] [<c10018ac>] (prepare_namespace) from [<c0ab7684>] 
(kernel_init+0x8/0x118)
[    7.259086] [<c0ab7684>] (kernel_init) from [<c0100114>] 
(ret_from_fork+0x14/0x20)tatic void __init populate_initrd_image(char *err)

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland