Patch "Revert "mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y"" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    Revert "mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y"

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     revert-mm-sparsemem-allocate-mem_section-at-runtime-for-config_sparsemem_extreme-y.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 77e3f5b8962b2d9eee0d0fc89e9188dd1c176f31 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Mon, 8 Jan 2018 10:06:56 +0100
Subject: Revert "mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y"

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 4afaf6ea65acb07e151470580d89e6a2c0268610 which is
commit 83e3c48729d9ebb7af5a31a504f3fd6aff0348c4 upstream.

It breaks kdump and probably shoudn't have been included in the 4.14.y
tree at all.

Reported-by: Michal Hocko <mhocko@kernel.org>
Reported-by: Mike Galbraith <efault@gmx.de>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@suse.de>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 include/linux/mmzone.h |    6 +-----
 mm/sparse.c            |   17 ++++++-----------
 2 files changed, 7 insertions(+), 16 deletions(-)

--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1152,17 +1152,13 @@ struct mem_section {
 #define SECTION_ROOT_MASK	(SECTIONS_PER_ROOT - 1)
 
 #ifdef CONFIG_SPARSEMEM_EXTREME
-extern struct mem_section **mem_section;
+extern struct mem_section *mem_section[NR_SECTION_ROOTS];
 #else
 extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
 #endif
 
 static inline struct mem_section *__nr_to_section(unsigned long nr)
 {
-#ifdef CONFIG_SPARSEMEM_EXTREME
-	if (!mem_section)
-		return NULL;
-#endif
 	if (!mem_section[SECTION_NR_TO_ROOT(nr)])
 		return NULL;
 	return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -23,7 +23,8 @@
  * 1) mem_section	- memory sections, mem_map's for valid memory
  */
 #ifdef CONFIG_SPARSEMEM_EXTREME
-struct mem_section **mem_section;
+struct mem_section *mem_section[NR_SECTION_ROOTS]
+	____cacheline_internodealigned_in_smp;
 #else
 struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
 	____cacheline_internodealigned_in_smp;
@@ -100,7 +101,7 @@ static inline int sparse_index_init(unsi
 int __section_nr(struct mem_section* ms)
 {
 	unsigned long root_nr;
-	struct mem_section *root = NULL;
+	struct mem_section* root;
 
 	for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
 		root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
@@ -111,7 +112,7 @@ int __section_nr(struct mem_section* ms)
 		     break;
 	}
 
-	VM_BUG_ON(!root);
+	VM_BUG_ON(root_nr == NR_SECTION_ROOTS);
 
 	return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
 }
@@ -339,17 +340,11 @@ again:
 static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
 {
 	unsigned long usemap_snr, pgdat_snr;
-	static unsigned long old_usemap_snr;
-	static unsigned long old_pgdat_snr;
+	static unsigned long old_usemap_snr = NR_MEM_SECTIONS;
+	static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;
 	struct pglist_data *pgdat = NODE_DATA(nid);
 	int usemap_nid;
 
-	/* First call */
-	if (!old_usemap_snr) {
-		old_usemap_snr = NR_MEM_SECTIONS;
-		old_pgdat_snr = NR_MEM_SECTIONS;
-	}
-
 	usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
 	pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
 	if (usemap_snr == pgdat_snr)


Patches currently in stable-queue which might be from gregkh@linuxfoundation.org are

queue-4.14/x86-tlb-drop-the-_gpl-from-the-cpu_tlbstate-export.patch
queue-4.14/crypto-chelsio-select-crypto_gf128mul.patch
queue-4.14/btrfs-fix-refcount_t-usage-when-deleting-btrfs_delayed_nodes.patch
queue-4.14/x86-cpu-always-show-current-cpu-frequency-in-proc-cpuinfo.patch
queue-4.14/crypto-chacha20poly1305-validate-the-digest-size.patch
queue-4.14/crypto-pcrypt-fix-freeing-pcrypt-instances.patch
queue-4.14/parisc-fix-alignment-of-pa_tlb_lock-in-assembly-on-32-bit-smp-kernel.patch
queue-4.14/crypto-n2-cure-use-after-free.patch
queue-4.14/kernel-signal.c-remove-the-no-longer-needed-signal_unkillable-check-in-complete_signal.patch
queue-4.14/kernel-signal.c-protect-the-signal_unkillable-tasks-from-sig_kernel_only-signals.patch
queue-4.14/x86-alternatives-add-missing-n-at-end-of-alternative-inline-asm.patch
queue-4.14/x86-kaslr-fix-the-vaddr_end-mess.patch
queue-4.14/revert-mm-sparsemem-allocate-mem_section-at-runtime-for-config_sparsemem_extreme-y.patch
queue-4.14/fscache-fix-the-default-for-fscache_maybe_release_page.patch
queue-4.14/kvm-s390-prevent-buffer-overrun-on-memory-hotplug-during-migration.patch
queue-4.14/powerpc-mm-fix-segv-on-mapped-region-to-return-segv_accerr.patch
queue-4.14/iommu-arm-smmu-v3-cope-with-duplicated-stream-ids.patch
queue-4.14/efi-capsule-loader-reinstate-virtual-capsule-mapping.patch
queue-4.14/kernel-acct.c-fix-the-acct-needcheck-check-in-check_free_space.patch
queue-4.14/parisc-qemu-idle-sleep-support.patch
queue-4.14/x86-cpu-avoid-unnecessary-ipis-in-arch_freq_get_on_cpu.patch
queue-4.14/x86-mm-set-modules_end-to-0xffffffffff000000.patch
queue-4.14/input-elantech-add-new-icbody-type-15.patch
queue-4.14/iommu-arm-smmu-v3-don-t-free-page-table-ops-twice.patch
queue-4.14/kernel-signal.c-protect-the-traced-signal_unkillable-tasks-from-sigkill.patch
queue-4.14/x86-microcode-amd-add-support-for-fam17h-microcode-loading.patch
queue-4.14/mm-sparse.c-wrong-allocation-for-mem_section.patch
queue-4.14/mm-mprotect-add-a-cond_resched-inside-change_pmd_range.patch
queue-4.14/drm-i915-apply-display-wa-1183-on-skl-kbl-and-cfl.patch
queue-4.14/kvm-s390-fix-cmma-migration-for-multiple-memory-slots.patch
queue-4.14/drm-i915-disable-dc-states-around-gmbus-on-glk.patch
queue-4.14/x86-events-intel-ds-use-the-proper-cache-flush-method-for-mapping-ds-buffers.patch
queue-4.14/sunxi-rsb-include-of-based-modalias-in-device-uevent.patch
queue-4.14/x86-pti-rename-bug_cpu_insecure-to-bug_cpu_meltdown.patch
queue-4.14/x86-mm-map-cpu_entry_area-at-the-same-place-on-4-5-level.patch
queue-4.14/userfaultfd-clear-the-vma-vm_userfaultfd_ctx-if-uffd_event_fork-fails.patch
queue-4.14/arc-uaccess-dont-use-l-gcc-inline-asm-constraint-modifier.patch
queue-4.14/apparmor-fix-regression-in-mount-mediation-when-feature-set-is-pinned.patch
queue-4.14/mtd-nand-pxa3xx-fix-readoob-implementation.patch