[PATCH 6.1.y 2/3] mm/vmemmap/devdax: fix kernel crash when probing devdax devices

[Sasha Levin <sashal@kernel.org>]

From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>

[ Upstream commit 87a7ae75d7383afa998f57656d1d14e2a730cc47 ]

commit 4917f55b4ef9 ("mm/sparse-vmemmap: improve memory savings for
compound devmaps") added support for using optimized vmmemap for devdax
devices.  But how vmemmap mappings are created are architecture specific.
For example, powerpc with hash translation doesn't have vmemmap mappings
in init_mm page table instead they are bolted table entries in the
hardware page table

vmemmap_populate_compound_pages() used by vmemmap optimization code is not
aware of these architecture-specific mapping.  Hence allow architecture to
opt for this feature.  I selected architectures supporting
HUGETLB_PAGE_OPTIMIZE_VMEMMAP option as also supporting this feature.

This patch fixes the below crash on ppc64.

BUG: Unable to handle kernel data access on write at 0xc00c000100400038
Faulting instruction address: 0xc000000001269d90
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
Modules linked in:
CPU: 7 PID: 1 Comm: swapper/0 Not tainted 6.3.0-rc5-150500.34-default+ #2 5c90a668b6bbd142599890245c2fb5de19d7d28a
Hardware name: IBM,9009-42G POWER9 (raw) 0x4e0202 0xf000005 of:IBM,FW950.40 (VL950_099) hv:phyp pSeries
NIP:  c000000001269d90 LR: c0000000004c57d4 CTR: 0000000000000000
REGS: c000000003632c30 TRAP: 0300   Not tainted  (6.3.0-rc5-150500.34-default+)
MSR:  8000000000009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 24842228  XER: 00000000
CFAR: c0000000004c57d0 DAR: c00c000100400038 DSISR: 42000000 IRQMASK: 0
....
NIP [c000000001269d90] __init_single_page.isra.74+0x14/0x4c
LR [c0000000004c57d4] __init_zone_device_page+0x44/0xd0
Call Trace:
[c000000003632ed0] [c000000003632f60] 0xc000000003632f60 (unreliable)
[c000000003632f10] [c0000000004c5ca0] memmap_init_zone_device+0x170/0x250
[c000000003632fe0] [c0000000005575f8] memremap_pages+0x2c8/0x7f0
[c0000000036330c0] [c000000000557b5c] devm_memremap_pages+0x3c/0xa0
[c000000003633100] [c000000000d458a8] dev_dax_probe+0x108/0x3e0
[c0000000036331a0] [c000000000d41430] dax_bus_probe+0xb0/0x140
[c0000000036331d0] [c000000000cef27c] really_probe+0x19c/0x520
[c000000003633260] [c000000000cef6b4] __driver_probe_device+0xb4/0x230
[c0000000036332e0] [c000000000cef888] driver_probe_device+0x58/0x120
[c000000003633320] [c000000000cefa6c] __device_attach_driver+0x11c/0x1e0
[c0000000036333a0] [c000000000cebc58] bus_for_each_drv+0xa8/0x130
[c000000003633400] [c000000000ceefcc] __device_attach+0x15c/0x250
[c0000000036334a0] [c000000000ced458] bus_probe_device+0x108/0x110
[c0000000036334f0] [c000000000ce92dc] device_add+0x7fc/0xa10
[c0000000036335b0] [c000000000d447c8] devm_create_dev_dax+0x1d8/0x530
[c000000003633640] [c000000000d46b60] __dax_pmem_probe+0x200/0x270
[c0000000036337b0] [c000000000d46bf0] dax_pmem_probe+0x20/0x70
[c0000000036337d0] [c000000000d2279c] nvdimm_bus_probe+0xac/0x2b0
[c000000003633860] [c000000000cef27c] really_probe+0x19c/0x520
[c0000000036338f0] [c000000000cef6b4] __driver_probe_device+0xb4/0x230
[c000000003633970] [c000000000cef888] driver_probe_device+0x58/0x120
[c0000000036339b0] [c000000000cefd08] __driver_attach+0x1d8/0x240
[c000000003633a30] [c000000000cebb04] bus_for_each_dev+0xb4/0x130
[c000000003633a90] [c000000000cee564] driver_attach+0x34/0x50
[c000000003633ab0] [c000000000ced878] bus_add_driver+0x218/0x300
[c000000003633b40] [c000000000cf1144] driver_register+0xa4/0x1b0
[c000000003633bb0] [c000000000d21a0c] __nd_driver_register+0x5c/0x100
[c000000003633c10] [c00000000206a2e8] dax_pmem_init+0x34/0x48
[c000000003633c30] [c0000000000132d0] do_one_initcall+0x60/0x320
[c000000003633d00] [c0000000020051b0] kernel_init_freeable+0x360/0x400
[c000000003633de0] [c000000000013764] kernel_init+0x34/0x1d0
[c000000003633e50] [c00000000000de14] ret_from_kernel_thread+0x5c/0x64

Link: https://lkml.kernel.org/r/20230411142214.64464-1-aneesh.kumar@linux.ibm.com
Fixes: 4917f55b4ef9 ("mm/sparse-vmemmap: improve memory savings for compound devmaps")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reported-by: Tarun Sahu <tsahu@linux.ibm.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: cd681403a870 ("mm/mm_init: fix uninitialized struct pages for ZONE_DEVICE")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/mm.h  | 12 ++++++++++++
 mm/mm_init.c        | 11 -----------
 mm/sparse-vmemmap.c |  3 +--
 3 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index ac0638a8c38dba..4f0aa81257c585 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3405,6 +3405,18 @@ void vmemmap_populate_print_last(void);
 void vmemmap_free(unsigned long start, unsigned long end,
 		struct vmem_altmap *altmap);
 #endif
+
+#define VMEMMAP_RESERVE_NR	2
+#ifdef CONFIG_ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
+#define vmemmap_can_optimize(altmap, pgmap)				\
+	(is_power_of_2(sizeof(struct page)) && (pgmap) && !(altmap) &&	\
+	 (((pgmap_vmemmap_nr(pgmap) * sizeof(struct page)) >> PAGE_SHIFT) > \
+	  VMEMMAP_RESERVE_NR))
+#else
+#define vmemmap_can_optimize(altmap, pgmap)	\
+	((void)(altmap), (void)(pgmap), false)
+#endif
+
 void register_page_bootmem_memmap(unsigned long section_nr, struct page *map,
 				  unsigned long nr_pages);
 
diff --git a/mm/mm_init.c b/mm/mm_init.c
index ccfccb45808ab1..5aab6903bddcbe 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -241,17 +241,6 @@ static void __ref __init_zone_device_page(struct page *page, unsigned long pfn,
 		set_page_count(page, 0);
 }
 
-#define VMEMMAP_RESERVE_NR	2
-#ifdef CONFIG_ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
-#define vmemmap_can_optimize(altmap, pgmap)				\
-	(is_power_of_2(sizeof(struct page)) && !(altmap) &&		\
-	 (((pgmap_vmemmap_nr(pgmap) * sizeof(struct page)) >> PAGE_SHIFT) > \
-	  VMEMMAP_RESERVE_NR))
-#else
-#define vmemmap_can_optimize(altmap, pgmap)	\
-	((void)(altmap), (void)(pgmap), false)
-#endif
-
 #define pageblock_migratetype_init_range(start_pfn, nr_pages, migratetype) \
 do {									\
 	unsigned long __start = (start_pfn);				\
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index f89dbaa05eef3e..28929fdf5d3bca 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -385,8 +385,7 @@ struct page * __meminit __populate_section_memmap(unsigned long pfn,
 		!IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))
 		return NULL;
 
-	if (is_power_of_2(sizeof(struct page)) &&
-	    pgmap && pgmap_vmemmap_nr(pgmap) > 1 && !altmap)
+	if (vmemmap_can_optimize(altmap, pgmap))
 		r = vmemmap_populate_compound_pages(pfn, start, end, nid, pgmap);
 	else
 		r = vmemmap_populate(start, end, nid, altmap);
-- 
2.53.0