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author | Tejun Heo <tj@kernel.org> | 2009-09-01 21:12:28 +0900 |
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committer | Tejun Heo <tj@kernel.org> | 2009-09-01 21:23:18 +0900 |
commit | 04a13c7c632e1fe04a5f6e6c83565d2559e37598 (patch) | |
tree | 5f0d78abea4655a58c06c70f106d6265b97fae74 /mm | |
parent | 142d44b0dd6741a64a7bdbe029110e7c1dcf1d23 (diff) | |
download | linux-3.10-04a13c7c632e1fe04a5f6e6c83565d2559e37598.tar.gz linux-3.10-04a13c7c632e1fe04a5f6e6c83565d2559e37598.tar.bz2 linux-3.10-04a13c7c632e1fe04a5f6e6c83565d2559e37598.zip |
percpu: don't assume existence of cpu0
percpu incorrectly assumed that cpu0 was always there which led to the
following warning and eventual oops on sparc machines w/o cpu0.
WARNING: at mm/percpu.c:651 pcpu_map+0xdc/0x100()
Modules linked in:
Call Trace:
[000000000045eb70] warn_slowpath_common+0x50/0xa0
[000000000045ebdc] warn_slowpath_null+0x1c/0x40
[00000000004d493c] pcpu_map+0xdc/0x100
[00000000004d59a4] pcpu_alloc+0x3e4/0x4e0
[00000000004d5af8] __alloc_percpu+0x18/0x40
[00000000005b112c] __percpu_counter_init+0x4c/0xc0
...
Unable to handle kernel NULL pointer dereference
...
I7: <sysfs_new_dirent+0x30/0x120>
Disabling lock debugging due to kernel taint
Caller[000000000053c1b0]: sysfs_new_dirent+0x30/0x120
Caller[000000000053c7a4]: create_dir+0x24/0xc0
Caller[000000000053c870]: sysfs_create_dir+0x30/0x80
Caller[00000000005990e8]: kobject_add_internal+0xc8/0x200
...
Kernel panic - not syncing: Attempted to kill the idle task!
This patch fixes the problem by backporting parts from devel branch to
make percpu core not depend on the existence of cpu0.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Meelis Roos <mroos@linux.ee>
Cc: David Miller <davem@davemloft.net>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/percpu.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/mm/percpu.c b/mm/percpu.c index 5fe37842e0e..3311c8919f3 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -197,7 +197,12 @@ static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk, static bool pcpu_chunk_page_occupied(struct pcpu_chunk *chunk, int page_idx) { - return *pcpu_chunk_pagep(chunk, 0, page_idx) != NULL; + /* + * Any possible cpu id can be used here, so there's no need to + * worry about preemption or cpu hotplug. + */ + return *pcpu_chunk_pagep(chunk, raw_smp_processor_id(), + page_idx) != NULL; } /* set the pointer to a chunk in a page struct */ @@ -297,6 +302,14 @@ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr) return pcpu_first_chunk; } + /* + * The address is relative to unit0 which might be unused and + * thus unmapped. Offset the address to the unit space of the + * current processor before looking it up in the vmalloc + * space. Note that any possible cpu id can be used here, so + * there's no need to worry about preemption or cpu hotplug. + */ + addr += raw_smp_processor_id() * pcpu_unit_size; return pcpu_get_page_chunk(vmalloc_to_page(addr)); } |