Define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() to ensure page tables are properly synchronized when calling p*d_populate_kernel(). It is inteneded to synchronize page tables via pgd_pouplate_kernel() when 5-level paging is in use and via p4d_pouplate_kernel() when 4-level paging is used.

This fixes intermittent boot failures on systems using 4-level paging and a large amount of persistent memory:

BUG: unable to handle page fault for address: ffffe70000000034 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP NOPTI RIP: 0010:__init_single_page+0x9/0x6d Call Trace: <TASK> __init_zone_device_page+0x17/0x5d memmap_init_zone_device+0x154/0x1bb pagemap_range+0x2e0/0x40f memremap_pages+0x10b/0x2f0 devm_memremap_pages+0x1e/0x60 dev_dax_probe+0xce/0x2ec [device_dax] dax_bus_probe+0x6d/0xc9 [... snip ...] </TASK>

It also fixes a crash in vmemmap_set_pmd() caused by accessing vmemmap before sync_global_pgds() [1]:

BUG: unable to handle page fault for address: ffffeb3ff1200000 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: Oops: 0002 [#1] PREEMPT SMP NOPTI Tainted: [W]=WARN RIP: 0010:vmemmap_set_pmd+0xff/0x230 <TASK> vmemmap_populate_hugepages+0x176/0x180 vmemmap_populate+0x34/0x80 __populate_section_memmap+0x41/0x90 sparse_add_section+0x121/0x3e0 __add_pages+0xba/0x150 add_pages+0x1d/0x70 memremap_pages+0x3dc/0x810 devm_memremap_pages+0x1c/0x60 xe_devm_add+0x8b/0x100 [xe] xe_tile_init_noalloc+0x6a/0x70 [xe] xe_device_probe+0x48c/0x740 [xe] [... snip ...]

Cc: stable@vger.kernel.org Fixes: 8d400913c231 ("x86/vmemmap: handle unpopulated sub-pmd ranges") Closes: https://lore.kernel.org/linux-mm/20250311114420.240341-1-gwan-gyeong.mun@int... [1] Suggested-by: Dave Hansen dave.hansen@linux.intel.com Signed-off-by: Harry Yoo harry.yoo@oracle.com --- arch/x86/include/asm/pgtable_64_types.h | 3 +++ arch/x86/mm/init_64.c | 5 +++++ 2 files changed, 8 insertions(+)

diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h index 4604f924d8b8..7eb61ef6a185 100644 --- a/arch/x86/include/asm/pgtable_64_types.h +++ b/arch/x86/include/asm/pgtable_64_types.h @@ -36,6 +36,9 @@ static inline bool pgtable_l5_enabled(void) #define pgtable_l5_enabled() cpu_feature_enabled(X86_FEATURE_LA57) #endif /* USE_EARLY_PGTABLE_L5 */

+#define ARCH_PAGE_TABLE_SYNC_MASK \ + (pgtable_l5_enabled() ? PGTBL_PGD_MODIFIED : PGTBL_P4D_MODIFIED) + extern unsigned int pgdir_shift; extern unsigned int ptrs_per_p4d;

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index fdb6cab524f0..3800479022e4 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -223,6 +223,11 @@ static void sync_global_pgds(unsigned long start, unsigned long end) sync_global_pgds_l4(start, end); }

+void arch_sync_kernel_mappings(unsigned long start, unsigned long end) +{ + sync_global_pgds(start, end); +} + /* * NOTE: This function is marked __ref because it calls __init function * (alloc_bootmem_pages). It's safe to do it ONLY when after_bootmem == 0.