On Thu, Oct 13, 2022 at 10:33:45AM +0200, Oscar Salvador wrote: > On Fri, Oct 07, 2022 at 10:07:06AM +0900, Naoya Horiguchi wrote: > > From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx> > > > > Currently PageHWPoison flag does not behave well when experiencing memory > > hotremove/hotplug. Any data field in struct page is unreliable when the > > associated memory is offlined, and the current mechanism can't tell whether > > a memory block is onlined because a new memory devices is installed or > > because previous failed offline operations are undone. Especially if > > there's a hwpoisoned memory, it's unclear what the best option is. > > > > So introduce a new mechanism to make struct memory_block remember that > > a memory block has hwpoisoned memory inside it. And make any online event > > fail if the onlining memory block contains hwpoison. struct memory_block > > is freed and reallocated over ACPI-based hotremove/hotplug, but not over > > sysfs-based hotremove/hotplug. So the new counter can distinguish these > > cases. > > > > Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx> > > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > I glanzed over it and looks good overall. > Have a small question though: Thank you for looking. > > > @@ -864,6 +878,7 @@ void remove_memory_block_devices(unsigned long start, unsigned long size) > > mem = find_memory_block_by_id(block_id); > > if (WARN_ON_ONCE(!mem)) > > continue; > > + num_poisoned_pages_sub(-1UL, memblk_nr_poison(mem)); > > Why does num_poisoned_pages_sub() have to make this distinction (!-1 == -1) > for the hot-remove stage? The first argument is used to find memory_block including the given pfn. And in the above context remove_memory_block_devices() already has the pointer "mem", so recalcurating it looked to me not necessary. Moreover, this code is about to free the memory_block so updating the counter inside it can be avoided. This is just a tiny optimization, and there can be better option. Thanks, Naoya Horiguchi
