On Tue, Jul 28, 2020 at 06:33:53PM +0200, Christoph Hellwig wrote:

Hi Al and Linus,

currently a lot of the file system calls in the early in code (and the
devtmpfs kthread) rely on the implicit set_fs(KERNEL_DS) during boot.
This is one of the few last remaining places we need to deal with to kill
off set_fs entirely, so this series adds new helpers that take kernel
pointers.  These helpers are in init/ and marked __init and thus will
be discarded after bootup.  A few also need to be duplicated in devtmpfs,
though unfortunately.

Reverting this series from next-20200803 fixed the crash below on shutdown.

[ 7303.287890][    T1] systemd-shutdown[1]: All loop devices detached.
[ 7303.287930][    T1] systemd-shutdown[1]: Detaching DM devices.
[ 7303.441674][    T1] printk: shutdown: 9 output lines suppressed due to ratelimiting
[ 7303.443999][    T1] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000100
[ 7303.444027][    T1] CPU: 120 PID: 1 Comm: shutdown Not tainted 5.8.0-next-20200803 #2
[ 7303.444053][    T1] Call Trace:
[ 7303.444069][    T1] [c000000015d27b70] [c0000000006f3778] dump_stack+0xfc/0x174 (unreliable)
[ 7303.444103][    T1] [c000000015d27bc0] [c0000000000c9328] panic+0x214/0x4ac
[ 7303.444140][    T1] [c000000015d27c60] [c0000000000d4d28] do_exit+0xda8/0xee0
[ 7303.444178][    T1] [c000000015d27d60] [c0000000000d4f1c] do_group_exit+0x5c/0xd0
list_empty at include/linux/list.h:282
(inlined by) thread_group_empty at include/linux/sched/signal.h:671
(inlined by) do_group_exit at kernel/exit.c:888
[ 7303.444205][    T1] [c000000015d27da0] [c0000000000d4fac] sys_exit_group+0x1c/0x20
sys_exit_group at kernel/exit.c:914
[ 7303.444234][    T1] [c000000015d27dc0] [c00000000002c628] system_call_exception+0xf8/0x1d0
[ 7303.444262][    T1] [c000000015d27e20] [c00000000000d0a8] system_call_common+0xe8/0x218
[ 7304.936912][    T1] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000100 ]---

The series sits on top of my previous

  "decruft the early init / initrd / initramfs code v2"

series.


Git tree:

    git://git.infradead.org/users/hch/misc.git init_path

Gitweb:

    http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/init_path


Changes since v3:
 - rename fs/for_init.c to fs/init.c
 - document the purpose of the routines in fs/init.c with a comment
 - don't mark devtmpfs __init as that will cause it to get overwritten
   by initmem poisoning
 - add an init_dup helper to make Al more happy than with the version
   commit to the "decruft the early init / initrd / initramfs code v2"
   series

Changes since v2:
 - move to fs/for_init.c
 - reuse the init routines in devtmpfs after refactoring devtmpfsd
   (and thus the broken error handling in the previous version)
 - actually use kern_path in a place where user_path_at sneaked back in

Changes since v1:
 - avoid most core VFS changes
 - renamed the functions and move them to init/ and devtmpfs
 - drop a bunch of cleanups that can be submitted independently now


Diffstat: