On Mon, Feb 10, 2020 at 03:12:52PM -0800, Alexander Duyck wrote: > On Mon, Jan 27, 2020 at 4:17 PM Minchan Kim <minchan@xxxxxxxxxx> wrote: > > > > There is a demand[1] to support pid as well pidfd for process_madvise > > to reduce unncessary syscall to get pidfd if the user has control of > > the targer process(ie, they could gaurantee the process is not gone > > or pid is not reused. Or, it might be okay to give a hint to wrong > > process). > > It looks like you misspelled several items in here including > "unnecessary", "target", and "guarantee". Thanks, will fix it. > > > This patch aims for supporting both options like waitid(2). So, the > > syscall is currently, > > > > int process_madvise(int which, pid_t pid, void *addr, > > size_t length, int advise, unsigned long flag); > > > > @which is actually idtype_t for userspace libray and currently, > > it supports P_PID and P_PIDFD. > > > > [1] https://lore.kernel.org/linux-mm/9d849087-3359-c4ab-fbec-859e8186c509@xxxxxxxxxxxxx/ > > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> > > --- > > include/linux/pid.h | 1 + > > include/linux/syscalls.h | 3 ++- > > kernel/exit.c | 17 ----------------- > > kernel/pid.c | 17 +++++++++++++++++ > > mm/madvise.c | 34 ++++++++++++++++++++++------------ > > 5 files changed, 42 insertions(+), 30 deletions(-) > > > > diff --git a/include/linux/pid.h b/include/linux/pid.h > > index 998ae7d24450..023d9c3a8edc 100644 > > --- a/include/linux/pid.h > > +++ b/include/linux/pid.h > > @@ -75,6 +75,7 @@ extern const struct file_operations pidfd_fops; > > struct file; > > > > extern struct pid *pidfd_pid(const struct file *file); > > +extern struct pid *pidfd_get_pid(unsigned int fd); > > > > static inline struct pid *get_pid(struct pid *pid) > > { > > So really this is two patches interleaved. You have the moving of the > pidfd_get_pid function and the update of the syscall. Personally I > would make the function move a separate patch and place it before you > define the syscall and fold the syscall changes into your original > patch. > > Doing that you wouldn't have to worry about the syscall changing in > behavior midway through a bisect. It would either be there or it > wouldn't. Will try it. Thanks!
