From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A511A248F51 for ; Thu, 21 Aug 2025 11:47:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755776850; cv=none; b=btuvfPeJIVoqWjPLMfIbrCRe219xG4WSd6VmYcfv//vUO+NXSBFKbS38ty//c1jGyzRSJTvGyqO5gE8xYCjHI4mUJCEOX7L/SeOdpbP2gomOnR/eY4VCa1O2vuLd8smvx/QzMzYC4WpXHOtYkc1iqe8d30ueN0DXPdZ5XS4HFCg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755776850; c=relaxed/simple; bh=dXP9AN+oFr5x8xqIK54Tm05XAlXLJqlR2yJuQA8cnGM=; h=Date:To:From:Subject:Message-Id; b=gEHOQJGCMkeGUNVi9g3ajGgJpAJr6uzTO2x4R770UknFG6mhYDl0H0eGhYSQfD7H2TVyGSaGhP8wDdo5uY73k6ylRcAROkYh0+yW/qXVmtUqfH+0iHfoQNS0CBtTGBu9lnFoPDUBN6wq6biyQUTZZtXLe8J8FYhwm4GhTb5tPYU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=aDV5Q77B; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="aDV5Q77B" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2BB6FC4CEEB; Thu, 21 Aug 2025 11:47:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1755776850; bh=dXP9AN+oFr5x8xqIK54Tm05XAlXLJqlR2yJuQA8cnGM=; h=Date:To:From:Subject:From; b=aDV5Q77B+RqllxHqSDOe2UvU7xT0RSTfmorNdJQgESlOCFw9sNCT47LfQkRf9SuYh YQRQDfwX3fGIiRN7yWXfUzgAD6SViQcWCpNJjNTCeKzPx6RA671307wnlYVOGDFmdP X4iEHe9Af2Kv9NzH68heYl6nD138gqiHb2fpTZ0E= Date: Thu, 21 Aug 2025 04:47:29 -0700 To: mm-commits@vger.kernel.org,lorenzo.stoakes@oracle.com,harry.yoo@oracle.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-introduce-and-use-pgdp4d_populate_kernel-fix.patch added to mm-hotfixes-unstable branch Message-Id: <20250821114730.2BB6FC4CEEB@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: fix KASAN build error due to p*d_populate_kernel() has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-introduce-and-use-pgdp4d_populate_kernel-fix.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-introduce-and-use-pgdp4d_populate_kernel-fix.patch This patch will later appear in the mm-hotfixes-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: Harry Yoo Subject: mm: fix KASAN build error due to p*d_populate_kernel() Date: Thu, 21 Aug 2025 18:35:42 +0900 KASAN unconditionally references kasan_early_shadow_{p4d,pud}. However, these global variables may not exist depending on the number of page table levels. For example, if CONFIG_PGTABLE_LEVELS=3, both variables do not exist. Although KASAN may refernce non-existent variables, it didn't break builds because calls to {pgd,p4d}_populate() are optimized away at compile time. However, {pgd,p4d}_populate_kernel() is defined as a function regardless of the number of page table levels, so the compiler may not optimize them away. In this case, the following linker error occurs: ld.lld: error: undefined symbol: kasan_early_shadow_p4d >>> referenced by init.c:260 (/home/hyeyoo/mm-new/mm/kasan/init.c:260) >>> mm/kasan/init.o:(kasan_populate_early_shadow) in archive vmlinux.a >>> referenced by init.c:260 (/home/hyeyoo/mm-new/mm/kasan/init.c:260) >>> mm/kasan/init.o:(kasan_populate_early_shadow) in archive vmlinux.a >>> did you mean: kasan_early_shadow_pmd >>> defined in: vmlinux.a(mm/kasan/init.o) ld.lld: error: undefined symbol: kasan_early_shadow_pud >>> referenced by init.c:263 (/home/hyeyoo/mm-new/mm/kasan/init.c:263) >>> mm/kasan/init.o:(kasan_populate_early_shadow) in archive vmlinux.a >>> referenced by init.c:263 (/home/hyeyoo/mm-new/mm/kasan/init.c:263) >>> mm/kasan/init.o:(kasan_populate_early_shadow) in archive vmlinux.a >>> referenced by init.c:200 (/home/hyeyoo/mm-new/mm/kasan/init.c:200) >>> mm/kasan/init.o:(zero_p4d_populate) in archive vmlinux.a >>> referenced 1 more times Therefore, to allow calls to {pgd,p4d}_populate_kernel() to be optimized out at compile time, define {pgd,p4d}_populate_kernel() as macros. This way, when pgd_populate() or p4d_populate() are simply empty macros, the corresponding *_populate_kernel() functions can also be optimized away. Link: https://lkml.kernel.org/r/20250821093542.37844-1-harry.yoo@oracle.com Signed-off-by: Harry Yoo Reviewed-by: Lorenzo Stoakes Signed-off-by: Andrew Morton --- include/linux/pgalloc.h | 26 ++++++++++++-------------- 1 file changed, 12 insertions(+), 14 deletions(-) --- a/include/linux/pgalloc.h~mm-introduce-and-use-pgdp4d_populate_kernel-fix +++ a/include/linux/pgalloc.h @@ -5,20 +5,18 @@ #include #include -static inline void pgd_populate_kernel(unsigned long addr, pgd_t *pgd, - p4d_t *p4d) -{ - pgd_populate(&init_mm, pgd, p4d); - if (ARCH_PAGE_TABLE_SYNC_MASK & PGTBL_PGD_MODIFIED) - arch_sync_kernel_mappings(addr, addr); -} +#define pgd_populate_kernel(addr, pgd, p4d) \ + do { \ + pgd_populate(&init_mm, pgd, p4d); \ + if (ARCH_PAGE_TABLE_SYNC_MASK & PGTBL_PGD_MODIFIED) \ + arch_sync_kernel_mappings(addr, addr); \ + } while (0) -static inline void p4d_populate_kernel(unsigned long addr, p4d_t *p4d, - pud_t *pud) -{ - p4d_populate(&init_mm, p4d, pud); - if (ARCH_PAGE_TABLE_SYNC_MASK & PGTBL_P4D_MODIFIED) - arch_sync_kernel_mappings(addr, addr); -} +#define p4d_populate_kernel(addr, p4d, pud) \ + do { \ + p4d_populate(&init_mm, p4d, pud); \ + if (ARCH_PAGE_TABLE_SYNC_MASK & PGTBL_P4D_MODIFIED) \ + arch_sync_kernel_mappings(addr, addr); \ + } while (0) #endif /* _LINUX_PGALLOC_H */ _ Patches currently in -mm which might be from harry.yoo@oracle.com are mm-move-page-table-sync-declarations-to-linux-pgtableh.patch mm-introduce-and-use-pgdp4d_populate_kernel.patch mm-introduce-and-use-pgdp4d_populate_kernel-fix.patch x86-mm-64-define-arch_page_table_sync_mask-and-arch_sync_kernel_mappings.patch