On Mon, Sep 08, 2025 at 12:10:43PM +0100, Lorenzo Stoakes wrote: > resctl uses remap_pfn_range(), but holds a mutex over the > operation. Therefore, establish the mutex in mmap_prepare(), release it in > mmap_complete() and release it in mmap_abort() should the operation fail.
The mutex can't do anything relative to remap_pfn, no reason to hold it. > @@ -1053,15 +1087,11 @@ static int pseudo_lock_dev_mmap(struct file *filp, > struct vm_area_struct *vma) > return -ENOSPC; > } > > - memset(plr->kmem + off, 0, vsize); > + /* No CoW allowed so don't need to specify pfn. */ > + remap_pfn_range_prepare(desc, 0); This would be a good place to make a more generic helper.. ret = remap_pfn_no_cow(desc, phys); And it can consistently check for !shared internally. Store phys in the desc and use common code to trigger the PTE population during complete. Jason
