Messages in this thread Patch in this message | | | From | Izik Eidus <> | Subject | [PATCH 2/6] ksm: dont allow overlap memory addresses registrations. | Date | Tue, 5 May 2009 01:25:31 +0300 |
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subjects say it all.
Signed-off-by: Izik Eidus <ieidus@redhat.com> --- mm/ksm.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 files changed, 54 insertions(+), 4 deletions(-)
diff --git a/mm/ksm.c b/mm/ksm.c index d58db6b..982dfff 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -451,21 +451,71 @@ static void remove_page_from_tree(struct mm_struct *mm, remove_rmap_item_from_tree(rmap_item); } +static inline int is_intersecting_address(unsigned long addr, + unsigned long begin, + unsigned long end) +{ + if (addr >= begin && addr < end) + return 1; + return 0; +} + +/* + * is_overlap_mem - check if there is overlapping with memory that was already + * registred. + * + * note - this function must to be called under slots_lock + */ +static int is_overlap_mem(struct ksm_memory_region *mem) +{ + struct ksm_mem_slot *slot; + + list_for_each_entry(slot, &slots, link) { + unsigned long mem_end; + unsigned long slot_end; + + cond_resched(); + + if (current->mm != slot->mm) + continue; + + mem_end = mem->addr + (unsigned long)mem->npages * PAGE_SIZE; + slot_end = slot->addr + (unsigned long)slot->npages * PAGE_SIZE; + + if (is_intersecting_address(mem->addr, slot->addr, slot_end) || + is_intersecting_address(mem_end - 1, slot->addr, slot_end)) + return 1; + if (is_intersecting_address(slot->addr, mem->addr, mem_end) || + is_intersecting_address(slot_end - 1, mem->addr, mem_end)) + return 1; + } + + return 0; +} + static int ksm_sma_ioctl_register_memory_region(struct ksm_sma *ksm_sma, struct ksm_memory_region *mem) { struct ksm_mem_slot *slot; int ret = -EPERM; + if (!mem->npages) + goto out; + + down_write(&slots_lock); + if ((ksm_sma->nregions + 1) > regions_per_fd) { ret = -EBUSY; - goto out; + goto out_unlock; } + if (is_overlap_mem(mem)) + goto out_unlock; + slot = kzalloc(sizeof(struct ksm_mem_slot), GFP_KERNEL); if (!slot) { ret = -ENOMEM; - goto out; + goto out_unlock; } /* @@ -478,8 +528,6 @@ static int ksm_sma_ioctl_register_memory_region(struct ksm_sma *ksm_sma, slot->addr = mem->addr; slot->npages = mem->npages; - down_write(&slots_lock); - list_add_tail(&slot->link, &slots); list_add_tail(&slot->sma_link, &ksm_sma->sma_slots); ksm_sma->nregions++; @@ -489,6 +537,8 @@ static int ksm_sma_ioctl_register_memory_region(struct ksm_sma *ksm_sma, out_free: kfree(slot); +out_unlock: + up_write(&slots_lock); out: return ret; } -- 1.5.6.5
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