[PATCH v3 2/2] mm, hwpoison: When copy-on-write hits poison, take page offline

From: Tony Luck
Date: Fri Oct 21 2022 - 16:01:38 EST


Cannot call memory_failure() directly from the fault handler because
mmap_lock (and others) are held.

It is important, but not urgent, to mark the source page as h/w poisoned
and unmap it from other tasks.

Use memory_failure_queue() to request a call to memory_failure() for the
page with the error.

Also provide a stub version for CONFIG_MEMORY_FAILURE=n

Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
include/linux/mm.h | 5 ++++-
mm/memory.c | 4 +++-
2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8bbcccbc5565..03ced659eb58 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3268,7 +3268,6 @@ enum mf_flags {
int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index,
unsigned long count, int mf_flags);
extern int memory_failure(unsigned long pfn, int flags);
-extern void memory_failure_queue(unsigned long pfn, int flags);
extern void memory_failure_queue_kick(int cpu);
extern int unpoison_memory(unsigned long pfn);
extern int sysctl_memory_failure_early_kill;
@@ -3277,8 +3276,12 @@ extern void shake_page(struct page *p);
extern atomic_long_t num_poisoned_pages __read_mostly;
extern int soft_offline_page(unsigned long pfn, int flags);
#ifdef CONFIG_MEMORY_FAILURE
+extern void memory_failure_queue(unsigned long pfn, int flags);
extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags);
#else
+static inline void memory_failure_queue(unsigned long pfn, int flags)
+{
+}
static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags)
{
return 0;
diff --git a/mm/memory.c b/mm/memory.c
index b6056eef2f72..eae242351726 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2866,8 +2866,10 @@ 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))
+ if (copy_mc_user_highpage(dst, src, addr, vma)) {
+ memory_failure_queue(page_to_pfn(src), 0);
return -EHWPOISON;
+ }
return 0;
}

--
2.37.3