Re: [PATCH RFC 09/11] misc/sgi-gru: use ptep_get() for page-table reads
From: Pedro Falcato <pfalcato@suse.de>
Date: 2026-07-29 12:37:15
Also in:
bpf, damon, dri-devel, intel-gfx, linux-arch, linux-fsdevel, linux-mm, linux-perf-users, lkml, xen-devel
On Mon, Jul 27, 2026 at 05:47:00PM +0100, Muhammad Usama Anjum wrote:
quoted hunk ↗ jump to hunk
A leaf PMD is being read through ptep_get() by treating the PMD address as PTE-sized table storage. ptep_get() now accepts hw_pte_t *, so update the cast accordingly. pte_offset_kernel() also returns hw_pte_t *. Get pte_t value by calling ptep_get(). Signed-off-by: Muhammad Usama Anjum <redacted> --- drivers/misc/sgi-gru/grufault.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c index 3557d78ee47a2..ff89d34ad2aa4 100644 --- a/drivers/misc/sgi-gru/grufault.c +++ b/drivers/misc/sgi-gru/grufault.c@@ -228,10 +228,10 @@ static int atomic_pte_lookup(struct vm_area_struct *vma, unsigned long vaddr, goto err; #ifdef CONFIG_X86_64 if (unlikely(pmd_leaf(*pmdp))) - pte = ptep_get((pte_t *)pmdp); + pte = ptep_get((hw_pte_t *)pmdp); else #endif - pte = *pte_offset_kernel(pmdp, vaddr); + pte = ptep_get(pte_offset_kernel(pmdp, vaddr)); if (unlikely(!pte_present(pte) || (write && (!pte_write(pte) || !pte_dirty(pte)))))
This code is super, super broken. Can we remove this ASAP? For starters, we're using is_vm_hugetlb_page() to detect page shift, the code does not grab refs on the pages, uses pte_offset_kernel() on user page tables, does not handle PUD-level hugepages, does not handle PMD-level hugepages on !x86_64, does not hold page table locks nor check for pte table retraction, etc I don't think I need to go on. -- Pedro