On 02/01/2018 07:33 PM, Andrey Ryabinin wrote:
> KASAN uses different routines to map shadow for hot added memory and memory
> obtained in boot process. Attempt to offline memory onlined by normal boot
> process leads to this:
>
> Trying to vfree() nonexistent vm area (000000005d3b34b9)
> WARNING: CPU: 2 PID: 13215 at mm/vmalloc.c:1525 __vunmap+0x147/0x190
>
> Call Trace:
> kasan_mem_notifier+0xad/0xb9
> notifier_call_chain+0x166/0x260
> __blocking_notifier_call_chain+0xdb/0x140
> __offline_pages+0x96a/0xb10
> memory_subsys_offline+0x76/0xc0
> device_offline+0xb8/0x120
> store_mem_state+0xfa/0x120
> kernfs_fop_write+0x1d5/0x320
> __vfs_write+0xd4/0x530
> vfs_write+0x105/0x340
> SyS_write+0xb0/0x140
>
> Obviously we can't call vfree() to free memory that wasn't allocated via
> vmalloc(). Use find_vm_area() to see if we can call vfree().
>
> Unfortunately it's a bit tricky to properly unmap and free shadow allocated
> during boot, so we'll have to keep it. If memory will come online again
> that shadow will be reused.
>
> Fixes: fa69b5989bb0 ("mm/kasan: add support for memory hotplug")
> Reported-by: Paul Menzel <pmenzel+linux-kasan-dev@xxxxxxxxxxxxx>
> Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> ---
This seems stuck in -mm. Andrew, can we proceed?
