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 AA078270577 for ; Thu, 28 Aug 2025 05:43:13 +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=1756359793; cv=none; b=P+mwNif9DWqB2v8gN/2dIV5034g+oU2Bz4eZ9du9IgrJB0+i3/k6bXkQc4Z1cmrOIr2tIti+XXAto6PI8tW1mZpNploScX3sIPPd2122Za5lHpi0RW7DevhNMeVrCts9xtRwdollUJgFL/Mc/qqwvgaCV1tWuZXcVxDCg4+BBk4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756359793; c=relaxed/simple; bh=hclyrzHbAAcOAoN5W+piJ9Sy+HryKHB9iw1Mr056tjQ=; h=Date:To:From:Subject:Message-Id; b=EvF1N1/58Fg/Tfa4wC5h3Hf+QyVPc4jHu5my0OOMyEnETs4RtYBRb09jh+cHpnkjccL06pYlowgINc3mkNkOrZNr5mlj/E0xNetGx0lTy7HAjxfspiQxR2G78BJzGdCw1DWoFZnOjma14wM/bdriJegV8IM+vmOIwan0sp6/FPc= 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=wVWIEe7t; 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="wVWIEe7t" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 24C3FC4CEEB; Thu, 28 Aug 2025 05:43:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1756359793; bh=hclyrzHbAAcOAoN5W+piJ9Sy+HryKHB9iw1Mr056tjQ=; h=Date:To:From:Subject:From; b=wVWIEe7tpZaXGK6O51JluqfeR//C0nzo9IXsGyXa24o/BVUbX5wTxF5zyRNdvvucV LDx6mPgF5+FPTEOSLPQy9uI5osY9viCUJq0+lVcqjUBKu08yXuJLZZefMPE7MIbWpg Ixm3+veXlOnVsCjyFQPdZvuF9Y3PmkbySVzYWoqI= Date: Wed, 27 Aug 2025 22:43:12 -0700 To: mm-commits@vger.kernel.org,sfr@canb.auug.org.au,lorenzo.stoakes@oracle.com,lkp@intel.com,dave.hansen@intel.com,harry.yoo@oracle.com,akpm@linux-foundation.org From: Andrew Morton Subject: [folded-merged] mm-introduce-and-use-pgdp4d_populate_kernel-fix.patch removed from -mm tree Message-Id: <20250828054313.24C3FC4CEEB@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm: fix KASAN build error due to p*d_populate_kernel() has been removed from the -mm tree. Its filename was mm-introduce-and-use-pgdp4d_populate_kernel-fix.patch This patch was dropped because it was folded into mm-introduce-and-use-pgdp4d_populate_kernel.patch ------------------------------------------------------ From: Harry Yoo Subject: mm: fix KASAN build error due to p*d_populate_kernel() Date: Fri, 22 Aug 2025 11:07:27 +0900 Address a linker error introduced by a patch currently in mm-hotfixes: "mm: introduce and use {pgd,p4d}_populate_kernel" [1]. 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/20250822020727.202749-1-harry.yoo@oracle.com Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202508181636.0Rtk0T7x-lkp@intel.com Reported-by: Stephen Rothwell Closes: https://lore.kernel.org/lkml/20250821160515.611d191e@canb.auug.org.au Link: https://lore.kernel.org/linux-mm/20250818020206.4517-3-harry.yoo@oracle.com [1] Signed-off-by: Harry Yoo Reviewed-by: Lorenzo Stoakes Cc: Dave Hansen Signed-off-by: Andrew Morton --- include/linux/pgalloc.h | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) --- a/include/linux/pgalloc.h~mm-introduce-and-use-pgdp4d_populate_kernel-fix +++ a/include/linux/pgalloc.h @@ -5,20 +5,25 @@ #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); -} +/* + * {pgd,p4d}_populate_kernel() are defined as macros to allow + * compile-time optimization based on the configured page table levels. + * Without this, linking may fail because callers (e.g., KASAN) may rely + * on calls to these functions being optimized away when passing symbols + * that exist only for certain page table levels. + */ +#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 x86-mm-64-define-arch_page_table_sync_mask-and-arch_sync_kernel_mappings.patch