On Fri 03-07-20 18:45:06, Colm MacCárthaigh wrote: > > > On 3 Jul 2020, at 4:30, Michal Hocko wrote: > > > On Fri 03-07-20 10:34:09, Catangiu, Adrian Costin wrote: > > > This patch adds logic to the kernel power code to zero out contents > > > of > > > all MADV_WIPEONSUSPEND VMAs present in the system during its > > > transition > > > to any suspend state equal or greater/deeper than Suspend-to-memory, > > > known as S3. > > > > How does the application learn that its memory got wiped? S2disk is an > > async operation and it can happen at any time during the task execution. > > So how does the application work to prevent from corrupted state - e.g. > > when suspended between two memory loads? > > The usual trick when using MADV_WIPEONFORK, or BSD’s MAP_INHERIT_ZERO, is to > store a guard variable in the page and to check the variable any time that > random data is generated. Well, MADV_WIPEONFORK is a completely different beast because the forking is under a full control of the parent process and the information about the fork can be forwarded to child process. It is not like the child would reborn into a new world in the middle of the execution. -- Michal Hocko SUSE Labs
