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@quicinc.com 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/4f091776142f2ebf7b94018146de72318474e686.164700875...
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@quicin...
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.