> On Apr 13, 2017, at 1:17 PM, Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx> wrote: > >> On 04/12/2017 10:31 AM, Hoeun Ryu wrote: >> vm_area_add_early/vm_area_register_early() are used to reserve vmalloc area >> during boot process and those virtually mapped areas are never unmapped. >> So `OR` VM_STATIC flag to the areas in vmalloc_init() when importing >> existing vmlist entries and prevent those areas from being removed from the >> rbtree by accident. > > I am wondering whether protection against accidental deletion > of any vmap area should be done in remove_vm_area() function > or the callers should take care of it. But I guess either way > it works. > >> >> Signed-off-by: Hoeun Ryu <hoeun.ryu@xxxxxxxxx> >> --- >> include/linux/vmalloc.h | 1 + >> mm/vmalloc.c | 9 ++++++--- >> 2 files changed, 7 insertions(+), 3 deletions(-) >> >> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h >> index 46991ad..3df53fc 100644 >> --- a/include/linux/vmalloc.h >> +++ b/include/linux/vmalloc.h >> @@ -19,6 +19,7 @@ struct notifier_block; /* in notifier.h */ >> #define VM_UNINITIALIZED 0x00000020 /* vm_struct is not fully initialized */ >> #define VM_NO_GUARD 0x00000040 /* don't add guard page */ >> #define VM_KASAN 0x00000080 /* has allocated kasan shadow memory */ >> +#define VM_STATIC 0x00000200 > > You might want to add some description in the comment saying > its a sticky VM area which will never go away or something. > OK. I will add some description. >> /* bits [20..32] reserved for arch specific ioremap internals */ >> >> /* >> diff --git a/mm/vmalloc.c b/mm/vmalloc.c >> index 8ef8ea1..fb5049a 100644 >> --- a/mm/vmalloc.c >> +++ b/mm/vmalloc.c >> @@ -1262,7 +1262,7 @@ void __init vmalloc_init(void) >> /* Import existing vmlist entries. */ >> for (tmp = vmlist; tmp; tmp = tmp->next) { >> va = kzalloc(sizeof(struct vmap_area), GFP_NOWAIT); >> - va->flags = VM_VM_AREA; >> + va->flags = VM_VM_AREA | VM_STATIC; >> va->va_start = (unsigned long)tmp->addr; >> va->va_end = va->va_start + tmp->size; >> va->vm = tmp; >> @@ -1480,7 +1480,7 @@ struct vm_struct *remove_vm_area(const void *addr) >> might_sleep(); >> >> va = find_vmap_area((unsigned long)addr); >> - if (va && va->flags & VM_VM_AREA) { >> + if (va && va->flags & VM_VM_AREA && likely(!(va->flags & VM_STATIC))) { > > > You might want to move the VM_STATIC check before the VM_VM_AREA > check so in cases where the former is set we can save one more > conditional check. > OK, I'll fix this in the next version Thank you for the review. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href