July 2025 - Linux-stable-mirror

[PATCH] spi: Add check for 8-bit transfer with 8 IO mode support

by Cheng Ming Lin

From: Cheng Ming Lin <chengminglin(a)mxic.com.tw> The current SPI framework does not verify if the SPI device supports 8 IO mode when doing an 8-bit transfer. This patch adds a check to ensure that if the transfer tx_nbits or rx_nbits is 8, the SPI mode must support 8 IO. If not, an error is returned, preventing undefined behavior. Fixes: d6a711a898672 ("spi: Fix OCTAL mode support") Cc: stable(a)vger.kernel.org Signed-off-by: Cheng Ming Lin <chengminglin(a)mxic.com.tw> --- drivers/spi/spi.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 1bc0fdbb1bd7..0ffa3f9f2870 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -4138,10 +4138,13 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message) xfer->tx_nbits != SPI_NBITS_OCTAL) return -EINVAL; if ((xfer->tx_nbits == SPI_NBITS_DUAL) && - !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD))) + !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL))) return -EINVAL; if ((xfer->tx_nbits == SPI_NBITS_QUAD) && - !(spi->mode & SPI_TX_QUAD)) + !(spi->mode & (SPI_TX_QUAD | SPI_TX_OCTAL))) + return -EINVAL; + if ((xfer->tx_nbits == SPI_NBITS_OCTAL) && + !(spi->mode & SPI_TX_OCTAL)) return -EINVAL; } /* Check transfer rx_nbits */ @@ -4154,10 +4157,13 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message) xfer->rx_nbits != SPI_NBITS_OCTAL) return -EINVAL; if ((xfer->rx_nbits == SPI_NBITS_DUAL) && - !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD))) + !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL))) return -EINVAL; if ((xfer->rx_nbits == SPI_NBITS_QUAD) && - !(spi->mode & SPI_RX_QUAD)) + !(spi->mode & (SPI_RX_QUAD | SPI_RX_OCTAL))) + return -EINVAL; + if ((xfer->rx_nbits == SPI_NBITS_OCTAL) && + !(spi->mode & SPI_RX_OCTAL)) return -EINVAL; } -- 2.25.1

1 week, 4 days

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[RFC V1 PATCH mm-hotfixes 1/3] mm: introduce and use {pgd,p4d}_populate_kernel()

by Harry Yoo

Intrdocue and use {pgd,p4d}_pouplate_kernel() in core MM code when populating PGD and P4D entries corresponding to the kernel address space. The main purpose of these helpers is to ensure synchronization of the kernel portion of the top-level page tables whenever such an entry is populated. Until now, the kernel has relied on each architecture to handle synchronization of top-level page tables in an ad-hoc manner. For example, see commit 9b861528a801 ("x86-64, mem: Update all PGDs for direct mapping and vmemmap mapping changes"). However, this approach has proven fragile, as it's easy to forget to perform the necessary synchronization when introducing new changes. To address this, introduce _kernel() varients of the page table population helpers that invoke architecture-specific hooks to properly synchronize the page tables. For now, it only targets x86_64, so only PGD and P4D level helpers are introduced. In theory, PUD and PMD level helpers can be added later if needed by other architectures. Currently it is no-op as no arch defines __HAVE_ARCH_SYNC_KERNEL_PGTABLES. Cc: <stable(a)vger.kernel.org> Suggested-by: Dave Hansen <dave.hansen(a)linux.intel.com> Signed-off-by: Harry Yoo <harry.yoo(a)oracle.com> --- include/asm-generic/pgalloc.h | 4 ++++ include/linux/pgalloc.h | 0 mm/kasan/init.c | 10 +++++----- mm/percpu.c | 4 ++-- mm/sparse-vmemmap.c | 4 ++-- 5 files changed, 13 insertions(+), 9 deletions(-) create mode 100644 include/linux/pgalloc.h diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h index 3c8ec3bfea44..6cac1ce64e01 100644 --- a/include/asm-generic/pgalloc.h +++ b/include/asm-generic/pgalloc.h @@ -295,6 +295,10 @@ static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd) __pgd_free(mm, pgd); } #endif +#ifndef __HAVE_ARCH_SYNC_KERNEL_PGTABLE +#define pgd_populate_kernel(addr, pgd, p4d) pgd_populate(&init_mm, pgd, p4d) +#define p4d_populate_kernel(addr, p4d, pud) p4d_populate(&init_mm, p4d, pud) +#endif #endif /* CONFIG_MMU */ diff --git a/include/linux/pgalloc.h b/include/linux/pgalloc.h new file mode 100644 index 000000000000..e69de29bb2d1 diff --git a/mm/kasan/init.c b/mm/kasan/init.c index ced6b29fcf76..43de820ee282 100644 --- a/mm/kasan/init.c +++ b/mm/kasan/init.c @@ -191,7 +191,7 @@ static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr, pud_t *pud; pmd_t *pmd; - p4d_populate(&init_mm, p4d, + p4d_populate_kernel(addr, p4d, lm_alias(kasan_early_shadow_pud)); pud = pud_offset(p4d, addr); pud_populate(&init_mm, pud, @@ -212,7 +212,7 @@ static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr, } else { p = early_alloc(PAGE_SIZE, NUMA_NO_NODE); pud_init(p); - p4d_populate(&init_mm, p4d, p); + p4d_populate_kernel(addr, p4d, p); } } zero_pud_populate(p4d, addr, next); @@ -251,10 +251,10 @@ int __ref kasan_populate_early_shadow(const void *shadow_start, * puds,pmds, so pgd_populate(), pud_populate() * is noops. */ - pgd_populate(&init_mm, pgd, + pgd_populate_kernel(addr, pgd, lm_alias(kasan_early_shadow_p4d)); p4d = p4d_offset(pgd, addr); - p4d_populate(&init_mm, p4d, + p4d_populate_kernel(addr, p4d, lm_alias(kasan_early_shadow_pud)); pud = pud_offset(p4d, addr); pud_populate(&init_mm, pud, @@ -273,7 +273,7 @@ int __ref kasan_populate_early_shadow(const void *shadow_start, if (!p) return -ENOMEM; } else { - pgd_populate(&init_mm, pgd, + pgd_populate_kernel(addr, pgd, early_alloc(PAGE_SIZE, NUMA_NO_NODE)); } } diff --git a/mm/percpu.c b/mm/percpu.c index 782cc148b39c..57450a03c432 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -3134,13 +3134,13 @@ void __init __weak pcpu_populate_pte(unsigned long addr) if (pgd_none(*pgd)) { p4d = memblock_alloc_or_panic(P4D_TABLE_SIZE, P4D_TABLE_SIZE); - pgd_populate(&init_mm, pgd, p4d); + pgd_populate_kernel(addr, pgd, p4d); } p4d = p4d_offset(pgd, addr); if (p4d_none(*p4d)) { pud = memblock_alloc_or_panic(PUD_TABLE_SIZE, PUD_TABLE_SIZE); - p4d_populate(&init_mm, p4d, pud); + p4d_populate_kernel(addr, p4d, pud); } pud = pud_offset(p4d, addr); diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c index fd2ab5118e13..e275310ac708 100644 --- a/mm/sparse-vmemmap.c +++ b/mm/sparse-vmemmap.c @@ -229,7 +229,7 @@ p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node) if (!p) return NULL; pud_init(p); - p4d_populate(&init_mm, p4d, p); + p4d_populate_kernel(addr, p4d, p); } return p4d; } @@ -241,7 +241,7 @@ pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node) void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); if (!p) return NULL; - pgd_populate(&init_mm, pgd, p); + pgd_populate_kernel(addr, pgd, p); } return pgd; } -- 2.43.0

1 week, 4 days

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Linux 6.12.38

by Greg Kroah-Hartman

I'm announcing the release of the 6.12.38 kernel. Only users of AMD x86-based processors need to upgrade, all others may skip this release. The updated 6.12.y git tree can be found at: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-6.12.y and can be browsed at the normal kernel.org git web browser: https://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=summary thanks, greg k-h ------------ Makefile | 2 +- arch/x86/kernel/cpu/amd.c | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) Borislav Petkov (AMD) (1): x86/CPU/AMD: Properly check the TSA microcode Greg Kroah-Hartman (1): Linux 6.12.38

1 week, 4 days

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Linux 6.6.98

by Greg Kroah-Hartman

I'm announcing the release of the 6.6.98 kernel. Only users of AMD x86-based processors need to upgrade, all others may skip this release. The updated 6.6.y git tree can be found at: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-6.6.y and can be browsed at the normal kernel.org git web browser: https://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=summary thanks, greg k-h ------------ Makefile | 2 +- arch/x86/kernel/cpu/amd.c | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) Borislav Petkov (AMD) (1): x86/CPU/AMD: Properly check the TSA microcode Greg Kroah-Hartman (1): Linux 6.6.98

1 week, 4 days

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Linux 6.1.145

by Greg Kroah-Hartman

I'm announcing the release of the 6.1.145 kernel. Only users of AMD x86-based processors need to upgrade, all others may skip this release. The updated 6.1.y git tree can be found at: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-6.1.y and can be browsed at the normal kernel.org git web browser: https://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=summary thanks, greg k-h ------------ Makefile | 2 +- arch/x86/kernel/cpu/amd.c | 5 +++-- 2 files changed, 4 insertions(+), 3 deletions(-) Borislav Petkov (AMD) (1): x86/CPU/AMD: Properly check the TSA microcode Greg Kroah-Hartman (1): Linux 6.1.145

1 week, 4 days

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Linux 5.15.188

by Greg Kroah-Hartman

I'm announcing the release of the 5.15.188 kernel. Only users of AMD x86-based processors need to upgrade, all others may skip this release. The updated 5.15.y git tree can be found at: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-5.15.y and can be browsed at the normal kernel.org git web browser: https://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=summary thanks, greg k-h ------------ Makefile | 2 +- arch/x86/kernel/cpu/amd.c | 5 +++-- 2 files changed, 4 insertions(+), 3 deletions(-) Borislav Petkov (AMD) (1): x86/CPU/AMD: Properly check the TSA microcode Greg Kroah-Hartman (1): Linux 5.15.188

1 week, 4 days

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FAILED: patch "[PATCH] x86/mm: Disable hugetlb page table sharing on 32-bit" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 76303ee8d54bff6d9a6d55997acd88a6c2ba63cf # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025071423-imbecile-slander-d8e9@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 76303ee8d54bff6d9a6d55997acd88a6c2ba63cf Mon Sep 17 00:00:00 2001 From: Jann Horn <jannh(a)google.com> Date: Wed, 2 Jul 2025 10:32:04 +0200 Subject: [PATCH] x86/mm: Disable hugetlb page table sharing on 32-bit Only select ARCH_WANT_HUGE_PMD_SHARE on 64-bit x86. Page table sharing requires at least three levels because it involves shared references to PMD tables; 32-bit x86 has either two-level paging (without PAE) or three-level paging (with PAE), but even with three-level paging, having a dedicated PGD entry for hugetlb is only barely possible (because the PGD only has four entries), and it seems unlikely anyone's actually using PMD sharing on 32-bit. Having ARCH_WANT_HUGE_PMD_SHARE enabled on non-PAE 32-bit X86 (which has 2-level paging) became particularly problematic after commit 59d9094df3d7 ("mm: hugetlb: independent PMD page table shared count"), since that changes `struct ptdesc` such that the `pt_mm` (for PGDs) and the `pt_share_count` (for PMDs) share the same union storage - and with 2-level paging, PMDs are PGDs. (For comparison, arm64 also gates ARCH_WANT_HUGE_PMD_SHARE on the configuration of page tables such that it is never enabled with 2-level paging.) Closes: https://lore.kernel.org/r/srhpjxlqfna67blvma5frmy3aa@altlinux.org Fixes: cfe28c5d63d8 ("x86: mm: Remove x86 version of huge_pmd_share.") Reported-by: Vitaly Chikunov <vt(a)altlinux.org> Suggested-by: Dave Hansen <dave.hansen(a)intel.com> Signed-off-by: Jann Horn <jannh(a)google.com> Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Acked-by: Oscar Salvador <osalvador(a)suse.de> Acked-by: David Hildenbrand <david(a)redhat.com> Tested-by: Vitaly Chikunov <vt(a)altlinux.org> Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250702-x86-2level-hugetlb-v2-1-1a98096edf92%4… diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 71019b3b54ea..4e0fe688cc83 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -147,7 +147,7 @@ config X86 select ARCH_WANTS_DYNAMIC_TASK_STRUCT select ARCH_WANTS_NO_INSTR select ARCH_WANT_GENERAL_HUGETLB - select ARCH_WANT_HUGE_PMD_SHARE + select ARCH_WANT_HUGE_PMD_SHARE if X86_64 select ARCH_WANT_LD_ORPHAN_WARN select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64

1 week, 4 days

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FAILED: patch "[PATCH] x86/mm: Disable hugetlb page table sharing on 32-bit" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 76303ee8d54bff6d9a6d55997acd88a6c2ba63cf # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025071422-target-professor-6f97@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 76303ee8d54bff6d9a6d55997acd88a6c2ba63cf Mon Sep 17 00:00:00 2001 From: Jann Horn <jannh(a)google.com> Date: Wed, 2 Jul 2025 10:32:04 +0200 Subject: [PATCH] x86/mm: Disable hugetlb page table sharing on 32-bit Only select ARCH_WANT_HUGE_PMD_SHARE on 64-bit x86. Page table sharing requires at least three levels because it involves shared references to PMD tables; 32-bit x86 has either two-level paging (without PAE) or three-level paging (with PAE), but even with three-level paging, having a dedicated PGD entry for hugetlb is only barely possible (because the PGD only has four entries), and it seems unlikely anyone's actually using PMD sharing on 32-bit. Having ARCH_WANT_HUGE_PMD_SHARE enabled on non-PAE 32-bit X86 (which has 2-level paging) became particularly problematic after commit 59d9094df3d7 ("mm: hugetlb: independent PMD page table shared count"), since that changes `struct ptdesc` such that the `pt_mm` (for PGDs) and the `pt_share_count` (for PMDs) share the same union storage - and with 2-level paging, PMDs are PGDs. (For comparison, arm64 also gates ARCH_WANT_HUGE_PMD_SHARE on the configuration of page tables such that it is never enabled with 2-level paging.) Closes: https://lore.kernel.org/r/srhpjxlqfna67blvma5frmy3aa@altlinux.org Fixes: cfe28c5d63d8 ("x86: mm: Remove x86 version of huge_pmd_share.") Reported-by: Vitaly Chikunov <vt(a)altlinux.org> Suggested-by: Dave Hansen <dave.hansen(a)intel.com> Signed-off-by: Jann Horn <jannh(a)google.com> Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Acked-by: Oscar Salvador <osalvador(a)suse.de> Acked-by: David Hildenbrand <david(a)redhat.com> Tested-by: Vitaly Chikunov <vt(a)altlinux.org> Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250702-x86-2level-hugetlb-v2-1-1a98096edf92%4… diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 71019b3b54ea..4e0fe688cc83 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -147,7 +147,7 @@ config X86 select ARCH_WANTS_DYNAMIC_TASK_STRUCT select ARCH_WANTS_NO_INSTR select ARCH_WANT_GENERAL_HUGETLB - select ARCH_WANT_HUGE_PMD_SHARE + select ARCH_WANT_HUGE_PMD_SHARE if X86_64 select ARCH_WANT_LD_ORPHAN_WARN select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64

1 week, 4 days

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FAILED: patch "[PATCH] x86/mm: Disable hugetlb page table sharing on 32-bit" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 76303ee8d54bff6d9a6d55997acd88a6c2ba63cf # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025071421-molar-theme-43d7@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 76303ee8d54bff6d9a6d55997acd88a6c2ba63cf Mon Sep 17 00:00:00 2001 From: Jann Horn <jannh(a)google.com> Date: Wed, 2 Jul 2025 10:32:04 +0200 Subject: [PATCH] x86/mm: Disable hugetlb page table sharing on 32-bit Only select ARCH_WANT_HUGE_PMD_SHARE on 64-bit x86. Page table sharing requires at least three levels because it involves shared references to PMD tables; 32-bit x86 has either two-level paging (without PAE) or three-level paging (with PAE), but even with three-level paging, having a dedicated PGD entry for hugetlb is only barely possible (because the PGD only has four entries), and it seems unlikely anyone's actually using PMD sharing on 32-bit. Having ARCH_WANT_HUGE_PMD_SHARE enabled on non-PAE 32-bit X86 (which has 2-level paging) became particularly problematic after commit 59d9094df3d7 ("mm: hugetlb: independent PMD page table shared count"), since that changes `struct ptdesc` such that the `pt_mm` (for PGDs) and the `pt_share_count` (for PMDs) share the same union storage - and with 2-level paging, PMDs are PGDs. (For comparison, arm64 also gates ARCH_WANT_HUGE_PMD_SHARE on the configuration of page tables such that it is never enabled with 2-level paging.) Closes: https://lore.kernel.org/r/srhpjxlqfna67blvma5frmy3aa@altlinux.org Fixes: cfe28c5d63d8 ("x86: mm: Remove x86 version of huge_pmd_share.") Reported-by: Vitaly Chikunov <vt(a)altlinux.org> Suggested-by: Dave Hansen <dave.hansen(a)intel.com> Signed-off-by: Jann Horn <jannh(a)google.com> Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Acked-by: Oscar Salvador <osalvador(a)suse.de> Acked-by: David Hildenbrand <david(a)redhat.com> Tested-by: Vitaly Chikunov <vt(a)altlinux.org> Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250702-x86-2level-hugetlb-v2-1-1a98096edf92%4… diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 71019b3b54ea..4e0fe688cc83 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -147,7 +147,7 @@ config X86 select ARCH_WANTS_DYNAMIC_TASK_STRUCT select ARCH_WANTS_NO_INSTR select ARCH_WANT_GENERAL_HUGETLB - select ARCH_WANT_HUGE_PMD_SHARE + select ARCH_WANT_HUGE_PMD_SHARE if X86_64 select ARCH_WANT_LD_ORPHAN_WARN select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64

1 week, 4 days

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FAILED: patch "[PATCH] x86/mm: Disable hugetlb page table sharing on 32-bit" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 76303ee8d54bff6d9a6d55997acd88a6c2ba63cf # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025071420-occupy-vowel-a8a5@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 76303ee8d54bff6d9a6d55997acd88a6c2ba63cf Mon Sep 17 00:00:00 2001 From: Jann Horn <jannh(a)google.com> Date: Wed, 2 Jul 2025 10:32:04 +0200 Subject: [PATCH] x86/mm: Disable hugetlb page table sharing on 32-bit Only select ARCH_WANT_HUGE_PMD_SHARE on 64-bit x86. Page table sharing requires at least three levels because it involves shared references to PMD tables; 32-bit x86 has either two-level paging (without PAE) or three-level paging (with PAE), but even with three-level paging, having a dedicated PGD entry for hugetlb is only barely possible (because the PGD only has four entries), and it seems unlikely anyone's actually using PMD sharing on 32-bit. Having ARCH_WANT_HUGE_PMD_SHARE enabled on non-PAE 32-bit X86 (which has 2-level paging) became particularly problematic after commit 59d9094df3d7 ("mm: hugetlb: independent PMD page table shared count"), since that changes `struct ptdesc` such that the `pt_mm` (for PGDs) and the `pt_share_count` (for PMDs) share the same union storage - and with 2-level paging, PMDs are PGDs. (For comparison, arm64 also gates ARCH_WANT_HUGE_PMD_SHARE on the configuration of page tables such that it is never enabled with 2-level paging.) Closes: https://lore.kernel.org/r/srhpjxlqfna67blvma5frmy3aa@altlinux.org Fixes: cfe28c5d63d8 ("x86: mm: Remove x86 version of huge_pmd_share.") Reported-by: Vitaly Chikunov <vt(a)altlinux.org> Suggested-by: Dave Hansen <dave.hansen(a)intel.com> Signed-off-by: Jann Horn <jannh(a)google.com> Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Acked-by: Oscar Salvador <osalvador(a)suse.de> Acked-by: David Hildenbrand <david(a)redhat.com> Tested-by: Vitaly Chikunov <vt(a)altlinux.org> Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250702-x86-2level-hugetlb-v2-1-1a98096edf92%4… diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 71019b3b54ea..4e0fe688cc83 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -147,7 +147,7 @@ config X86 select ARCH_WANTS_DYNAMIC_TASK_STRUCT select ARCH_WANTS_NO_INSTR select ARCH_WANT_GENERAL_HUGETLB - select ARCH_WANT_HUGE_PMD_SHARE + select ARCH_WANT_HUGE_PMD_SHARE if X86_64 select ARCH_WANT_LD_ORPHAN_WARN select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64

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Linux-stable-mirror July 2025