diff options
Diffstat (limited to 'include/linux/ksm.h')
| -rw-r--r-- | include/linux/ksm.h | 31 |
1 files changed, 27 insertions, 4 deletions
diff --git a/include/linux/ksm.h b/include/linux/ksm.h index a485c14ecd5..2d64ff30c0d 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -12,11 +12,14 @@ #include <linux/sched.h> #include <linux/vmstat.h> +struct mmu_gather; + #ifdef CONFIG_KSM int ksm_madvise(struct vm_area_struct *vma, unsigned long start, unsigned long end, int advice, unsigned long *vm_flags); int __ksm_enter(struct mm_struct *mm); -void __ksm_exit(struct mm_struct *mm); +void __ksm_exit(struct mm_struct *mm, + struct mmu_gather **tlbp, unsigned long end); static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) { @@ -25,10 +28,24 @@ static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) return 0; } -static inline void ksm_exit(struct mm_struct *mm) +/* + * For KSM to handle OOM without deadlock when it's breaking COW in a + * likely victim of the OOM killer, exit_mmap() has to serialize with + * ksm_exit() after freeing mm's pages but before freeing its page tables. + * That leaves a window in which KSM might refault pages which have just + * been finally unmapped: guard against that with ksm_test_exit(), and + * use it after getting mmap_sem in ksm.c, to check if mm is exiting. + */ +static inline bool ksm_test_exit(struct mm_struct *mm) +{ + return atomic_read(&mm->mm_users) == 0; +} + +static inline void ksm_exit(struct mm_struct *mm, + struct mmu_gather **tlbp, unsigned long end) { if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) - __ksm_exit(mm); + __ksm_exit(mm, tlbp, end); } /* @@ -64,7 +81,13 @@ static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) return 0; } -static inline void ksm_exit(struct mm_struct *mm) +static inline bool ksm_test_exit(struct mm_struct *mm) +{ + return 0; +} + +static inline void ksm_exit(struct mm_struct *mm, + struct mmu_gather **tlbp, unsigned long end) { } |