Re: [PATCH v1 10/36] mm: sanity-check maximum folio size in folio_set_order()
From: Lorenzo Stoakes <hidden>
Date: 2025-08-28 15:01:49
Also in:
dri-devel, intel-gfx, io-uring, kvm, linux-arm-kernel, linux-crypto, linux-ide, linux-iommu, linux-kselftest, linux-mips, linux-mm, linux-mmc, linux-riscv, linux-s390, linux-scsi, lkml, virtualization
On Thu, Aug 28, 2025 at 12:01:14AM +0200, David Hildenbrand wrote:
Let's sanity-check in folio_set_order() whether we would be trying to create a folio with an order that would make it exceed MAX_FOLIO_ORDER. This will enable the check whenever a folio/compound page is initialized through prepare_compound_head() / prepare_compound_page().
NIT: with CONFIG_DEBUG_VM set :)
Reviewed-by: Zi Yan <ziy@nvidia.com> Signed-off-by: David Hildenbrand <redacted>
LGTM (apart from nit below), so: Reviewed-by: Lorenzo Stoakes <redacted>
quoted hunk ↗ jump to hunk
--- mm/internal.h | 1 + 1 file changed, 1 insertion(+)diff --git a/mm/internal.h b/mm/internal.h index 45da9ff5694f6..9b0129531d004 100644 --- a/mm/internal.h +++ b/mm/internal.h@@ -755,6 +755,7 @@ static inline void folio_set_order(struct folio *folio, unsigned int order) { if (WARN_ON_ONCE(!order || !folio_test_large(folio))) return; + VM_WARN_ON_ONCE(order > MAX_FOLIO_ORDER);
Given we have 'full-fat' WARN_ON*()'s above, maybe worth making this one too?
folio->_flags_1 = (folio->_flags_1 & ~0xffUL) | order; #ifdef NR_PAGES_IN_LARGE_FOLIO -- 2.50.1