On Wed, Mar 3, 2021 at 4:51 AM Aili Yao <yaoa...@kingsoft.com> wrote: > > On Wed, 3 Mar 2021 20:24:02 +0800 > Aili Yao <yaoa...@kingsoft.com> wrote: > > > On Mon, 1 Mar 2021 11:09:36 -0800 > > Andy Lutomirski <l...@amacapital.net> wrote: > > > > > > On Mar 1, 2021, at 11:02 AM, Luck, Tony <tony.l...@intel.com> wrote: > > > > > > > > > > > >> > > > >> Some programs may use read(2), write(2), etc as ways to check if > > > >> memory is valid without getting a signal. They might not want > > > >> signals, which means that this feature might need to be configurable. > > > > > > > > That sounds like an appalling hack. If users need such a mechanism > > > > we should create some better way to do that. > > > > > > > > > > Appalling hack or not, it works. So, if we’re going to send a signal to > > > user code that looks like it originated from a bina fide architectural > > > recoverable fault, it needs to be recoverable. A load from a failed > > > NVDIMM page is such a fault. A *kernel* load is not. So we need to > > > distinguish it somehow. > > > > Sorry for my previous mis-understanding, and i have some questions: > > if programs use read,write to check if if memory is valid, does it really > > want to cover the poison case?
I don't know. > > When for such a case, an error is returned, can the program realize it's > > hwposion issue not other software error and process correctly? Again, I don't know. But changing the API like this seems potentialy dangerous and needs to be done with care. > > > > if this is the proper action, the original posion flow in current code from > > read and write need to change too. > > > > Sorry, another question: > When programs use read(2), write(2) as ways to check if memory is valid, > does it really want to check if the user page the program provided is valid, > not the destination or disk space valid? They may well be trying to see if their memory is valid. > the patch will not affect this purpose as it's only valid for user page > which program provide to write or some syscall similiar parameter > > -- > Thanks! > Aili Yao -- Andy Lutomirski AMA Capital Management, LLC
