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

[Tony Luck]

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