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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-29 11:32:28 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-29 11:32:28 -0700 |
| commit | 6345d24daf0c1fffe6642081d783cdf653ebaa5c (patch) | |
| tree | 415a253621279111bd481d48cbb86174c70b952a /init | |
| parent | cab0d85c8dfcad4d799f9c294571440c6f1db091 (diff) | |
| download | lwn-6345d24daf0c1fffe6642081d783cdf653ebaa5c.tar.gz lwn-6345d24daf0c1fffe6642081d783cdf653ebaa5c.zip | |
mm: Fix boot crash in mm_alloc()
Thomas Gleixner reports that we now have a boot crash triggered by
CONFIG_CPUMASK_OFFSTACK=y:
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<c11ae035>] find_next_bit+0x55/0xb0
Call Trace:
[<c11addda>] cpumask_any_but+0x2a/0x70
[<c102396b>] flush_tlb_mm+0x2b/0x80
[<c1022705>] pud_populate+0x35/0x50
[<c10227ba>] pgd_alloc+0x9a/0xf0
[<c103a3fc>] mm_init+0xec/0x120
[<c103a7a3>] mm_alloc+0x53/0xd0
which was introduced by commit de03c72cfce5 ("mm: convert
mm->cpu_vm_cpumask into cpumask_var_t"), and is due to wrong ordering of
mm_init() vs mm_init_cpumask
Thomas wrote a patch to just fix the ordering of initialization, but I
hate the new double allocation in the fork path, so I ended up instead
doing some more radical surgery to clean it all up.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Ingo Molnar <mingo@elte.hu>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'init')
| -rw-r--r-- | init/main.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/init/main.c b/init/main.c index d2f1e086bf33..cafba67c13bf 100644 --- a/init/main.c +++ b/init/main.c @@ -487,6 +487,7 @@ asmlinkage void __init start_kernel(void) printk(KERN_NOTICE "%s", linux_banner); setup_arch(&command_line); mm_init_owner(&init_mm, &init_task); + mm_init_cpumask(&init_mm); setup_command_line(command_line); setup_nr_cpu_ids(); setup_per_cpu_areas(); @@ -510,7 +511,6 @@ asmlinkage void __init start_kernel(void) sort_main_extable(); trap_init(); mm_init(); - BUG_ON(mm_init_cpumask(&init_mm, 0)); /* * Set up the scheduler prior starting any interrupts (such as the |