On Wed, 24 Jun 2026 12:26:36 +0200 Boris Brezillon <[email protected]> wrote:
> On Tue, 23 Jun 2026 20:19:42 +0200 > "Christian A. Ehrhardt" <[email protected]> wrote: > > > When checking a different patch[1] sashiko AI pointed out that > > panthor needs the same fix[2]: > > > > In the ->huge_fault handler do not install a PMD huge page > > mapping if the huge page exceeds the boundaries of the VMA. > > > > [1] https://lore.kernel.org/lkml/[email protected]/ > > [2] https://sashiko.dev/#/patchset/20260622215718.1532689-1-lk%40c--e.de > > > > Cc: Boris Brezillon <[email protected]> > > Cc: Steven Price <[email protected]> > > Cc: Liviu Dudau <[email protected]> > > Fixes: 68cbf96b1e9b ("drm/panthor: Part ways with drm_gem_shmem_object") > > Signed-off-by: Christian A. Ehrhardt <[email protected]> > > I know the discussion is ongoing to decide what we should do about > these huge_fault() handlers, but I think it's worth getting this fix in > in the meantime. > > Reviewed-by: Boris Brezillon <[email protected]> BTW, I saw shashiko complain about our page_offset calculation which should look something like page_offset = vmf->pgoff - drm_vma_node_start(&bo->base.vma_node); to be immune to the vma->vm_{start,pgoff} adjustments done when the VMA is split. > > > --- > > drivers/gpu/drm/panthor/panthor_gem.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > NOTE: > > The panthor version is only compile tested because I don't > > have the hardware. However, the code is identical to that > > fixed in [1] and I have a reproducer for that. > > > > No need for for stable backports. The code is new in 7.1. > > > > diff --git a/drivers/gpu/drm/panthor/panthor_gem.c > > b/drivers/gpu/drm/panthor/panthor_gem.c > > index a1e2eb1ca7bb..54535bae2b0c 100644 > > --- a/drivers/gpu/drm/panthor/panthor_gem.c > > +++ b/drivers/gpu/drm/panthor/panthor_gem.c > > @@ -802,9 +802,13 @@ static vm_fault_t insert_page(struct vm_fault *vmf, > > unsigned int order, struct p > > } else if (order == PMD_ORDER) { > > unsigned long pfn = page_to_pfn(page); > > unsigned long paddr = pfn << PAGE_SHIFT; > > + struct vm_area_struct *vma = vmf->vma; > > + unsigned long start = ALIGN_DOWN(vmf->address, PMD_SIZE); > > + unsigned long end = start + PMD_SIZE; > > + bool in_range = vma->vm_start <= start && end <= vma->vm_end; > > bool aligned = (vmf->address & ~PMD_MASK) == (paddr & > > ~PMD_MASK); > > > > - if (aligned && > > + if (aligned && in_range && > > folio_test_pmd_mappable(page_folio(page))) { > > pfn &= PMD_MASK >> PAGE_SHIFT; > > return vmf_insert_pfn_pmd(vmf, pfn, vmf->flags & > > FAULT_FLAG_WRITE); >
