On Wed, 31 Aug 2016, Andrew Morton wrote: > > Attempting to online memory which is already online will cause this: > > > > 1. store_mem_state() called with buf="online" > > 2. device_online() returns 1 because device is already online > > 3. store_mem_state() returns 1 > > 4. calling code interprets this as 1-byte buffer read > > 5. store_mem_state() called again with buf="nline" > > 6. store_mem_state() returns -EINVAL > > > > Example: > > > > $ cat /sys/devices/system/memory/memory0/state > > online > > $ echo online > /sys/devices/system/memory/memory0/state > > -bash: echo: write error: Invalid argument > > > > Fix the return value of store_mem_state() so this doesn't happen. > > So.. what *does* happen after the patch? Is some sort of failure still > reported? Or am I correct in believing that the operation will appear > to have succeeded? If so, is that desirable? > It's not desirable, before commit 4f3549d72 this would have returned EINVAL since __memory_block_change_state() does not see the state as MEM_OFFLINE when the write is done. The correct fix is for store_mem_state() to return -EINVAL when device_online() returns non-zero. -- 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=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>