On Tue 22-03-22 17:24:58, Minchan Kim wrote: > On Tue, Mar 22, 2022 at 02:46:48PM -0700, Andrew Morton wrote: > > From: Charan Teja Kalla <quic_charante@xxxxxxxxxxx> > > Subject: mm: madvise: skip unmapped vma holes passed to process_madvise > > > > The process_madvise() system call is expected to skip holes in vma passed > > through 'struct iovec' vector list. But do_madvise, which > > process_madvise() calls for each vma, returns ENOMEM in case of unmapped > > holes, despite the VMA is processed. > > > > Thus process_madvise() should treat ENOMEM as expected and consider the > > VMA passed to as processed and continue processing other vma's in the > > vector list. Returning -ENOMEM to user, despite the VMA is processed, > > will be unable to figure out where to start the next madvise. > > > > Link: https://lkml.kernel.org/r/4f091776142f2ebf7b94018146de72318474e686.1647008754.git.quic_charante@xxxxxxxxxxx > > I thought it was still under discussion and Charan will post next > version along with previous patch > "mm: madvise: return correct bytes advised with process_madvise" > > https://lore.kernel.org/linux-mm/7207b2f5-6b3e-aea4-aa1b-9c6d849abe34@xxxxxxxxxxx/ Yes, I am not even sure the new semantic is sensible[1]. We should discuss that and see all the consequences. Changing the semantic of an existing syscall is always tricky going back and forth is even worse. -- Michal Hocko SUSE Labs
