In this patchset, we remove the unused macro EX_TYPE_COPY and centralize
the processing of memory-failure to do_machine_check() to avoid calling
memory_failure_queue() separately for different MC-Safe scenarios. In
addition, MCE_IN_KERNEL_COPYIN is renamed MCE_IN_KERNEL_COPY_MC to expand
its usage scope.
[1]https://lore.kernel.org/linux-mm/[email protected]/
since v2:
1. remove redundant fixup type EX_TYPE_COPY.
2. rename MCE_IN_KERNEL_COPYIN to MCE_IN_KERNEL_COPY_MC.
3. update patch3's commit message and the processing logic of
EX_TYPE_DEFAULT_MCE_SAFE based on the discussion of [1].
Kefeng Wang (1):
x86/mce: set MCE_IN_KERNEL_COPY_MC for DEFAULT_MCE_SAFE exception
Tong Tiangen (2):
x86/mce: remove redundant fixup type EX_TYPE_COPY
x86/mce: rename MCE_IN_KERNEL_COPYIN to MCE_IN_KERNEL_COPY_MC
arch/x86/include/asm/asm.h | 3 ---
arch/x86/include/asm/extable_fixup_types.h | 23 +++++++++++-----------
arch/x86/include/asm/mce.h | 8 ++++----
arch/x86/kernel/cpu/mce/core.c | 2 +-
arch/x86/kernel/cpu/mce/severity.c | 7 +++----
arch/x86/mm/extable.c | 9 ---------
mm/ksm.c | 1 -
mm/memory.c | 12 +++--------
8 files changed, 22 insertions(+), 43 deletions(-)
--
2.25.1
From: Kefeng Wang <[email protected]>
If an MCE has happened in kernel space and the kernel can recover,
mce.kflags MCE_IN_KERNEL_RECOV will set in error_context().
With the setting of MCE_IN_KERNEL_RECOV, the MCE is handled in
do_machine_check(). But due to lack of MCE_IN_KERNEL_COPY_MC, although the
kernel won't panic, the corrupted page don't be isolated, new one maybe
consume it again, which is not what we expected.
In order to avoid above issue, some hwpoison recover process[1][2][3][4],
memory_failure_queue() is called to cope with such unhandled corrupted
pages, also there are some other already existed MC-safe copy scenarios,
eg, nvdimm, dm-writecache, dax, which don't isolate corrupted pages.
The best way to fix them is set MCE_IN_KERNEL_COPY_MC for MC-Safe Copy,
then let the core do_machine_check() to isolate corrupted page instead
of doing it one-by-one.
EX_TYPE_FAULT_MCE_SAFE is used for the FPU. Here, we do not touch the logic
of FPU. We only modify the logic of EX_TYPE_DEFAULT_MCE_SAFE which is used
in the scenarios described above.
[1] commit d302c2398ba2 ("mm, hwpoison: when copy-on-write hits poison, take page offline")
[2] commit 1cb9dc4b475c ("mm: hwpoison: support recovery from HugePage copy-on-write faults")
[3] commit 6b970599e807 ("mm: hwpoison: support recovery from ksm_might_need_to_copy()")
[4] commit 1cb9dc4b475c ("mm: hwpoison: support recovery from HugePage copy-on-write faults")
Reviewed-by: Naoya Horiguchi <[email protected]>
Reviewed-by: Tony Luck <[email protected]>
Signed-off-by: Kefeng Wang <[email protected]>
Signed-off-by: Tong Tiangen <[email protected]>
---
arch/x86/kernel/cpu/mce/severity.c | 4 ++--
mm/ksm.c | 1 -
mm/memory.c | 12 +++---------
3 files changed, 5 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
index df67a7a13034..b4b1d028cbb3 100644
--- a/arch/x86/kernel/cpu/mce/severity.c
+++ b/arch/x86/kernel/cpu/mce/severity.c
@@ -292,11 +292,11 @@ static noinstr int error_context(struct mce *m, struct pt_regs *regs)
case EX_TYPE_UACCESS:
if (!copy_user)
return IN_KERNEL;
+ fallthrough;
+ case EX_TYPE_DEFAULT_MCE_SAFE:
m->kflags |= MCE_IN_KERNEL_COPY_MC;
fallthrough;
-
case EX_TYPE_FAULT_MCE_SAFE:
- case EX_TYPE_DEFAULT_MCE_SAFE:
m->kflags |= MCE_IN_KERNEL_RECOV;
return IN_KERNEL_RECOV;
diff --git a/mm/ksm.c b/mm/ksm.c
index ae05fb438ac5..01e3a7ef1b9d 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -3075,7 +3075,6 @@ struct folio *ksm_might_need_to_copy(struct folio *folio,
if (copy_mc_user_highpage(folio_page(new_folio, 0), page,
addr, vma)) {
folio_put(new_folio);
- memory_failure_queue(folio_pfn(folio), 0);
return ERR_PTR(-EHWPOISON);
}
folio_set_dirty(new_folio);
diff --git a/mm/memory.c b/mm/memory.c
index 809746555827..9f0d875b1d3f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2836,10 +2836,8 @@ static inline int __wp_page_copy_user(struct page *dst, struct page *src,
unsigned long addr = vmf->address;
if (likely(src)) {
- if (copy_mc_user_highpage(dst, src, addr, vma)) {
- memory_failure_queue(page_to_pfn(src), 0);
+ if (copy_mc_user_highpage(dst, src, addr, vma))
return -EHWPOISON;
- }
return 0;
}
@@ -6168,10 +6166,8 @@ static int copy_user_gigantic_page(struct folio *dst, struct folio *src,
cond_resched();
if (copy_mc_user_highpage(dst_page, src_page,
- addr + i*PAGE_SIZE, vma)) {
- memory_failure_queue(page_to_pfn(src_page), 0);
+ addr + i*PAGE_SIZE, vma))
return -EHWPOISON;
- }
}
return 0;
}
@@ -6187,10 +6183,8 @@ static int copy_subpage(unsigned long addr, int idx, void *arg)
struct copy_subpage_arg *copy_arg = arg;
if (copy_mc_user_highpage(copy_arg->dst + idx, copy_arg->src + idx,
- addr, copy_arg->vma)) {
- memory_failure_queue(page_to_pfn(copy_arg->src + idx), 0);
+ addr, copy_arg->vma))
return -EHWPOISON;
- }
return 0;
}
--
2.25.1
In commit 034ff37d3407 ("x86: rewrite '__copy_user_nocache' function"),
rewrited __copy_user_nocache() uses EX_TYPE_UACCESS instead of
EX_TYPE_COPY，this change does not broken the MC safe copy for
__copy_user_nocache(), but as a result, there's no place for EX_TYPE_COPY
to use. Therefore, we remove the definition of EX_TYPE_COPY.
Signed-off-by: Tong Tiangen <[email protected]>
---
arch/x86/include/asm/asm.h | 3 ---
arch/x86/include/asm/extable_fixup_types.h | 23 +++++++++++-----------
arch/x86/kernel/cpu/mce/severity.c | 1 -
arch/x86/mm/extable.c | 9 ---------
4 files changed, 11 insertions(+), 25 deletions(-)
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index fbcfec4dc4cc..692409ea0c37 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -215,9 +215,6 @@ register unsigned long current_stack_pointer asm(_ASM_SP);
#define _ASM_EXTABLE_UA(from, to) \
_ASM_EXTABLE_TYPE(from, to, EX_TYPE_UACCESS)
-#define _ASM_EXTABLE_CPY(from, to) \
- _ASM_EXTABLE_TYPE(from, to, EX_TYPE_COPY)
-
#define _ASM_EXTABLE_FAULT(from, to) \
_ASM_EXTABLE_TYPE(from, to, EX_TYPE_FAULT)
diff --git a/arch/x86/include/asm/extable_fixup_types.h b/arch/x86/include/asm/extable_fixup_types.h
index 991e31cfde94..6126af55b85b 100644
--- a/arch/x86/include/asm/extable_fixup_types.h
+++ b/arch/x86/include/asm/extable_fixup_types.h
@@ -36,18 +36,17 @@
#define EX_TYPE_DEFAULT 1
#define EX_TYPE_FAULT 2
#define EX_TYPE_UACCESS 3
-#define EX_TYPE_COPY 4
-#define EX_TYPE_CLEAR_FS 5
-#define EX_TYPE_FPU_RESTORE 6
-#define EX_TYPE_BPF 7
-#define EX_TYPE_WRMSR 8
-#define EX_TYPE_RDMSR 9
-#define EX_TYPE_WRMSR_SAFE 10 /* reg := -EIO */
-#define EX_TYPE_RDMSR_SAFE 11 /* reg := -EIO */
-#define EX_TYPE_WRMSR_IN_MCE 12
-#define EX_TYPE_RDMSR_IN_MCE 13
-#define EX_TYPE_DEFAULT_MCE_SAFE 14
-#define EX_TYPE_FAULT_MCE_SAFE 15
+#define EX_TYPE_CLEAR_FS 4
+#define EX_TYPE_FPU_RESTORE 5
+#define EX_TYPE_BPF 6
+#define EX_TYPE_WRMSR 7
+#define EX_TYPE_RDMSR 8
+#define EX_TYPE_WRMSR_SAFE 9 /* reg := -EIO */
+#define EX_TYPE_RDMSR_SAFE 10 /* reg := -EIO */
+#define EX_TYPE_WRMSR_IN_MCE 11
+#define EX_TYPE_RDMSR_IN_MCE 12
+#define EX_TYPE_DEFAULT_MCE_SAFE 13
+#define EX_TYPE_FAULT_MCE_SAFE 14
#define EX_TYPE_POP_REG 16 /* sp += sizeof(long) */
#define EX_TYPE_POP_ZERO (EX_TYPE_POP_REG | EX_DATA_IMM(0))
diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
index c4477162c07d..bca780fa5e57 100644
--- a/arch/x86/kernel/cpu/mce/severity.c
+++ b/arch/x86/kernel/cpu/mce/severity.c
@@ -290,7 +290,6 @@ static noinstr int error_context(struct mce *m, struct pt_regs *regs)
switch (fixup_type) {
case EX_TYPE_UACCESS:
- case EX_TYPE_COPY:
if (!copy_user)
return IN_KERNEL;
m->kflags |= MCE_IN_KERNEL_COPYIN;
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 271dcb2deabc..2354c0156e51 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -163,13 +163,6 @@ static bool ex_handler_uaccess(const struct exception_table_entry *fixup,
return ex_handler_default(fixup, regs);
}
-static bool ex_handler_copy(const struct exception_table_entry *fixup,
- struct pt_regs *regs, int trapnr)
-{
- WARN_ONCE(trapnr == X86_TRAP_GP, "General protection fault in user access. Non-canonical address?");
- return ex_handler_fault(fixup, regs, trapnr);
-}
-
static bool ex_handler_msr(const struct exception_table_entry *fixup,
struct pt_regs *regs, bool wrmsr, bool safe, int reg)
{
@@ -267,8 +260,6 @@ int fixup_exception(struct pt_regs *regs, int trapnr, unsigned long error_code,
return ex_handler_fault(e, regs, trapnr);
case EX_TYPE_UACCESS:
return ex_handler_uaccess(e, regs, trapnr, fault_addr);
- case EX_TYPE_COPY:
- return ex_handler_copy(e, regs, trapnr);
case EX_TYPE_CLEAR_FS:
return ex_handler_clear_fs(e, regs);
case EX_TYPE_FPU_RESTORE:
--
2.25.1