On 2022/6/29 15:14, Aneesh Kumar K V wrote:
On 6/29/22 12:00 PM, Kefeng Wang wrote:
Hi,
On 2022/6/29 13:09, Aneesh Kumar K.V wrote:
With commit ffa0b64e3be5 ("powerpc: Fix virt_addr_valid() for 64-bit Book3E & 32-bit")
the kernel now validate the addr against high_memory value. This results
in the below BUG_ON with dax pfns.
[ 635.798741][T26531] kernel BUG at mm/page_alloc.c:5521!
1:mon> e
cpu 0x1: Vector: 700 (Program Check) at [c000000007287630]
pc: c00000000055ed48: free_pages.part.0+0x48/0x110
lr: c00000000053ca70: tlb_finish_mmu+0x80/0xd0
sp: c0000000072878d0
msr: 800000000282b033
current = 0xc00000000afabe00
paca = 0xc00000037ffff300 irqmask: 0x03 irq_happened: 0x05
pid = 26531, comm = 50-landscape-sy
kernel BUG at :5521!
Linux version 5.19.0-rc3-14659-g4ec05be7c2e1 (kvaneesh@ltc-boston8) (gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #625 SMP Thu Jun 23 00:35:43 CDT 2022
1:mon> t
[link register ] c00000000053ca70 tlb_finish_mmu+0x80/0xd0
[c0000000072878d0] c00000000053ca54 tlb_finish_mmu+0x64/0xd0 (unreliable)
[c000000007287900] c000000000539424 exit_mmap+0xe4/0x2a0
[c0000000072879e0] c00000000019fc1c mmput+0xcc/0x210
[c000000007287a20] c000000000629230 begin_new_exec+0x5e0/0xf40
[c000000007287ae0] c00000000070b3cc load_elf_binary+0x3ac/0x1e00
[c000000007287c10] c000000000627af0 bprm_execve+0x3b0/0xaf0
[c000000007287cd0] c000000000628414 do_execveat_common.isra.0+0x1e4/0x310
[c000000007287d80] c00000000062858c sys_execve+0x4c/0x60
[c000000007287db0] c00000000002c1b0 system_call_exception+0x160/0x2c0
[c000000007287e10] c00000000000c53c system_call_common+0xec/0x250
The fix is to make sure we update high_memory on memory hotplug.
This is similar to what x86 does in commit 3072e413e305 ("mm/memory_hotplug: introduce add_pages")
Fixes: ffa0b64e3be5 ("powerpc: Fix virt_addr_valid() for 64-bit Book3E & 32-bit")
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
---
Changes from v2:
* drop WARN_ON_ONCE
* check for error from __add_pages
arch/powerpc/Kconfig | 4 ++++
arch/powerpc/mm/mem.c | 33 ++++++++++++++++++++++++++++++++-
2 files changed, 36 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index c2ce2e60c8f0..7aa12e88c580 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -358,6 +358,10 @@ config ARCH_SUSPEND_NONZERO_CPU
def_bool y
depends on PPC_POWERNV || PPC_PSERIES
+config ARCH_HAS_ADD_PAGES
+ def_bool y
+ depends on ARCH_ENABLE_MEMORY_HOTPLUG
+
config PPC_DCR_NATIVE
bool
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 52b77684acda..a97128a48817 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -105,6 +105,37 @@ void __ref arch_remove_linear_mapping(u64 start, u64 size)
vm_unmap_aliases();
}
+/*
+ * After memory hotplug the variables max_pfn, max_low_pfn and high_memory need
+ * updating.
+ */
+static void update_end_of_memory_vars(u64 start, u64 size)
+{
+ unsigned long end_pfn = PFN_UP(start + size);
+
+ if (end_pfn > max_pfn) {
+ max_pfn = end_pfn;
+ max_low_pfn = end_pfn;
+ high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
+ }
+}
+
+int __ref add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages,
+ struct mhp_params *params)
+{
+ int ret;
int ret = -EINVAL;
+
+ ret = __add_pages(nid, start_pfn, nr_pages, params);
+ if (ret)
+ return ret;
+
considering we are updating ret immediately why should we initialize that to EINVAL?
int ret = -EINVAL;
ret = __add_pages(nid, start_pfn, nr_pages, params);
Ignore it, I don't know what I was thinking...
+ /* update max_pfn, max_low_pfn and high_memory */
+ update_end_of_memory_vars(start_pfn << PAGE_SHIFT,
+ nr_pages << PAGE_SHIFT);
+
+ return ret;
+}
+
and could we only call update_end_of_memory_vars() in arch_add_memory()?
int __ref arch_add_memory(int nid, u64 start, u64 size,
struct mhp_params *params)
{
@@ -115,7 +146,7 @@ int __ref arch_add_memory(int nid, u64 start, u64 size,
rc = arch_create_linear_mapping(nid, start, size, params);
if (rc)
return rc;
- rc = __add_pages(nid, start_pfn, nr_pages, params);
+ rc = add_pages(nid, start_pfn, nr_pages, params);
if (rc)
arch_remove_linear_mapping(start, size);
if (!rc)
update_end_of_memory_vars(start_pfn << PAGE_SHIFT, nr_pages << PAGE_SHIFT);
else
arch_remove_linear_mapping(start, size);
Thanks
commit 3072e413e305 goes into the details of why it is done in add_pages
mm/memory_hotplug: introduce add_pages
There are new users of memory hotplug emerging. Some of them require
different subset of arch_add_memory. There are some which only require
allocation of struct pages without mapping those pages to the kernel
address space. We currently have __add_pages for that purpose. But this
is rather lowlevel and not very suitable for the code outside of the
memory hotplug. E.g. x86_64 wants to update max_pfn which should be done
by the caller. Introduce add_pages() which should care about those
details if they are needed. Each architecture should define its
implementation and select CONFIG_ARCH_HAS_ADD_PAGES. All others use the
currently existing __add_pages.
We could debate whether max_pfn/high_memory should encompass device private memory too.
But the current code on x86 does that and I would also expect virt_addr_valid to return
true for the address mapping private device memory.
OK, I see for private device memory will call add_pages(), which should
update
the max_pfn/high_memory, not only for arch_add_memory(). Maybe some
other archs
have the same problem.
Reviewed-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
return rc;
.
