The patch titled Subject: mm/gup: check p4d presence before going on has been added to the -mm mm-unstable branch. Its filename is mm-gup-check-p4d-presence-before-going-on.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-gup-check-p4d-presence-before-going-on.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Peter Xu <peterx@xxxxxxxxxx> Subject: mm/gup: check p4d presence before going on Date: Mon, 18 Mar 2024 16:03:53 -0400 Currently there should have no p4d swap entries so it may not matter much, however this may help us to rule out swap entries in pXd_huge() API, which will include p4d_huge(). The p4d_present() checks make it 100% clear that we won't rely on p4d_huge() for swap entries. Link: https://lkml.kernel.org/r/20240318200404.448346-4-peterx@xxxxxxxxxx Signed-off-by: Peter Xu <peterx@xxxxxxxxxx> Cc: Alistair Popple <apopple@xxxxxxxxxx> Cc: Andreas Larsson <andreas@xxxxxxxxxxx> Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Bjorn Andersson <andersson@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: David S. Miller <davem@xxxxxxxxxxxxx> Cc: Fabio Estevam <festevam@xxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Jason Gunthorpe <jgg@xxxxxxxxxx> Cc: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> Cc: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx> Cc: Mark Salter <msalter@xxxxxxxxxx> Cc: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx> Cc: Muchun Song <muchun.song@xxxxxxxxx> Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx> Cc: "Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxx> Cc: Nicholas Piggin <npiggin@xxxxxxxxx> Cc: Russell King <linux@xxxxxxxxxxxxxxx> Cc: Shawn Guo <shawnguo@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/gup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/gup.c~mm-gup-check-p4d-presence-before-going-on +++ a/mm/gup.c @@ -776,7 +776,7 @@ static struct page *follow_p4d_mask(stru p4dp = p4d_offset(pgdp, address); p4d = READ_ONCE(*p4dp); - if (p4d_none(p4d)) + if (!p4d_present(p4d)) return no_page_table(vma, flags); BUILD_BUG_ON(p4d_huge(p4d)); if (unlikely(p4d_bad(p4d))) @@ -3079,7 +3079,7 @@ static int gup_p4d_range(pgd_t *pgdp, pg p4d_t p4d = READ_ONCE(*p4dp); next = p4d_addr_end(addr, end); - if (p4d_none(p4d)) + if (!p4d_present(p4d)) return 0; BUILD_BUG_ON(p4d_huge(p4d)); if (unlikely(is_hugepd(__hugepd(p4d_val(p4d))))) { _ Patches currently in -mm which might be from peterx@xxxxxxxxxx are mm-memory-fix-missing-pte-marker-for-page-on-pte-zaps.patch mm-hmm-process-pud-swap-entry-without-pud_huge.patch mm-gup-cache-p4d-in-follow_p4d_mask.patch mm-gup-check-p4d-presence-before-going-on.patch mm-x86-change-pxd_huge-behavior-to-exclude-swap-entries.patch mm-sparc-change-pxd_huge-behavior-to-exclude-swap-entries.patch mm-arm-use-macros-to-define-pmd-pud-helpers.patch mm-arm-redefine-pmd_huge-with-pmd_leaf.patch mm-arm64-merge-pxd_huge-and-pxd_leaf-definitions.patch mm-powerpc-redefine-pxd_huge-with-pxd_leaf.patch mm-gup-merge-pxd-huge-mapping-checks.patch mm-treewide-replace-pxd_huge-with-pxd_leaf.patch mm-treewide-remove-pxd_huge.patch mm-arm-remove-pmd_thp_or_huge.patch mm-document-pxd_leaf-api.patch