On 18.05.2018 17:57, David Hildenbrand wrote: > On 01.02.2018 17:33, 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. >> > > While debugging kasan memory hotplug problems I am having, stumbled over > this patch. > > Couldn't we handle that via VM_KASAN like in kasan_module_alloc/free > instead? > Just realized that this will most probably not work. So please ignore my comment for now :) -- Thanks, David / dhildenb
