diff options
| 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 /include | |
| parent | cab0d85c8dfcad4d799f9c294571440c6f1db091 (diff) | |
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 'include')
| -rw-r--r-- | include/linux/mm_types.h | 14 | ||||
| -rw-r--r-- | include/linux/sched.h | 1 |
2 files changed, 12 insertions, 3 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 2a78aae78c6..027935c86c6 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -264,6 +264,8 @@ struct mm_struct { struct linux_binfmt *binfmt; + cpumask_var_t cpu_vm_mask_var; + /* Architecture-specific MM context */ mm_context_t context; @@ -311,10 +313,18 @@ struct mm_struct { #ifdef CONFIG_TRANSPARENT_HUGEPAGE pgtable_t pmd_huge_pte; /* protected by page_table_lock */ #endif - - cpumask_var_t cpu_vm_mask_var; +#ifdef CONFIG_CPUMASK_OFFSTACK + struct cpumask cpumask_allocation; +#endif }; +static inline void mm_init_cpumask(struct mm_struct *mm) +{ +#ifdef CONFIG_CPUMASK_OFFSTACK + mm->cpu_vm_mask_var = &mm->cpumask_allocation; +#endif +} + /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */ static inline cpumask_t *mm_cpumask(struct mm_struct *mm) { diff --git a/include/linux/sched.h b/include/linux/sched.h index bcddd013810..2a8621c4be1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2194,7 +2194,6 @@ static inline void mmdrop(struct mm_struct * mm) if (unlikely(atomic_dec_and_test(&mm->mm_count))) __mmdrop(mm); } -extern int mm_init_cpumask(struct mm_struct *mm, struct mm_struct *oldmm); /* mmput gets rid of the mappings and all user-space */ extern void mmput(struct mm_struct *); |