Vasiliy Kulikov [Wed, 3 Aug 2011 00:52:32 +0000 (10:52 +1000)]
On thread exit shm_exit_ns() is called, it uses shm_ids(ns).rw_mutex. It
is initialized in shm_init(), but it is not called yet at the moment of
kernel threads exit. Some kernel threads are created in
do_pre_smp_initcalls(), and shm_init() is called in do_initcalls().
Static initialization of shm_ids(init_ipc_ns).rw_mutex fixes the race.
It fixes a kernel oops:
Unable to handle kernel NULL pointer dereference at virtual address 00000000
...
[<c0320090>] (__down_write_nested+0x88/0xe0) from [<c015da08>] (exit_shm+0x28/0x48)
[<c015da08>] (exit_shm+0x28/0x48) from [<c002e550>] (do_exit+0x59c/0x750)
[<c002e550>] (do_exit+0x59c/0x750) from [<c003eaac>] (____call_usermodehelper+0x13c/0x154)
[<c003eaac>] (____call_usermodehelper+0x13c/0x154) from [<c000f630>] (kernel_thread_exit+0x0/0x8)
Code: 1afffffae597c00ce58d0000e587d00c (e58cd000)
Reported-by: Manuel Lauss <manuel.lauss@googlemail.com> Reported-by: Richard Weinberger <richard@nod.at> Reported-by: Marc Zyngier <maz@misterjones.org> Tested-by: Manuel Lauss <manuel.lauss@googlemail.com> Tested-by: Richard Weinberger <richard@nod.at> Tested-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Vasiliy Kulikov <segoon@openwall.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Will Drewry [Wed, 3 Aug 2011 00:52:30 +0000 (10:52 +1000)]
This patch makes two changes:
- check for trailing characters after parsing PARTNROFF=%d
- disable root_wait if a syntax error is seen
The former assures that bad input like
root=PARTUUID=<validuuid>/PARTNROFF=5abc
properly fails by attempting to parse an extra character after the
integer. If the integer is missing, sscanf will fail, but if it is
present, and there is a trailing non-nul character, then the extra
field will be parsed and the error case will be hit.
The latter assures that if rootwait has been specified, the error
message isn't flooded to the screen during rootwait's loop. Instead of
adding printk ratelimiting, root_wait was disabled. This stays true to
the rootwait goal of support asynchronous device arrival while still
providing users with helpful messages. With ratelimiting or disabling
logging on rootwait, a range of edge cases turn up where the user would
not be informed of an error properly.
Signed-off-by: Will Drewry <wad@chromium.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Randy Dunlap <rdunlap@xenotime.net> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Will Drewry [Wed, 3 Aug 2011 00:52:30 +0000 (10:52 +1000)]
Expand root=PARTUUID=UUID syntax to support selecting a root partition by
integer offset from a known, unique partition. This approach provides
similar properties to specifying a device and partition number, but using
the UUID as the unique path prior to evaluating the offset.
For example,
root=PARTUUID=99DE9194-FC15-4223-9192-FC243948F88B/PARTNROFF=1
selects the partition with UUID 99DE.. then select the next
partition.
This change is motivated by a particular usecase in Chromium OS where the
bootloader can easily determine what partition it is on (by UUID) but
doesn't perform general partition table walking.
That said, support for this model provides a direct mechanism for the user
to modify the root partition to boot without specifically needing to
extract each UUID or update the bootloader explicitly when the root
partition UUID is changed (if it is recreated to be larger, for instance).
Pinning to a /boot-style partition UUID allows the arbitrary root
partition reconfiguration/modifications with slightly less ambiguity than
just [dev][partition] and less stringency than the specific root partition
UUID.
Signed-off-by: Will Drewry <wad@chromium.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Randy Dunlap <rdunlap@xenotime.net> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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