Re: [PATCH RFC 07/11] mm/mremap: use ptep_get() for the destination PTE
Muhammad Usama Anjum <[email protected]> Thu, 30 Jul 2026 13:59:24 +0100
| Newsgroups | org.kernel.vger.linux-parisc,dev.linux.lists.damon,org.freedesktop.lists.dri-devel,org.freedesktop.lists.intel-gfx,org.kernel.vger.bpf,org.kernel.vger.linux-arch,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-kernel,org.kernel.vger.linux-perf-users,org.kernel.vger.linux-trace-kernel,org.kvack.linux-mm,org.xenproject.lists.xen-devel |
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| Message-ID | <[email protected]> |
On 30/07/2026 12:29 pm, Alexander Gordeev wrote: > On Mon, Jul 27, 2026 at 05:46:58PM +0100, Muhammad Usama Anjum wrote: >> move_ptes() directly dereferences new_ptep when checking that the >> destination slot is empty. new_ptep now points to hw_pte_t table storage, >> while pte_none() consumes a logical pte_t value. >> >> Read the destination entry through the standard ptep_get() accessor before >> passing the logical value to pte_none(). >> >> Signed-off-by: Muhammad Usama Anjum <[email protected]> >> --- >> mm/mremap.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/mm/mremap.c b/mm/mremap.c >> index d966ee8248b6b..ecb90ccee6fdd 100644 >> --- a/mm/mremap.c >> +++ b/mm/mremap.c >> @@ -264,7 +264,7 @@ static int move_ptes(struct pagetable_move_control *pmc, >> >> for (; old_addr < old_end; old_ptep += nr_ptes, old_addr += nr_ptes * PAGE_SIZE, >> new_ptep += nr_ptes, new_addr += nr_ptes * PAGE_SIZE) { >> - VM_WARN_ON_ONCE(!pte_none(*new_ptep)); >> + VM_WARN_ON_ONCE(!pte_none(ptep_get(new_ptep))); > > Same as the previous patch, except that I did it already: > https://lore.kernel.org/linux-mm/[email protected]/ I'll drop this patch. > >> >> nr_ptes = 1; >> max_nr_ptes = (old_end - old_addr) >> PAGE_SHIFT; >> -- >> 2.47.3 >> -- Thanks, Usama