[mm-unstable,8/8] mm/memory-failure: convert unpoison_memory() to folios

Commit Message

Sidhartha Kumar Jan. 12, 2023, 8:46 p.m. UTC

Use a folio inside unpoison_memory which replaces a compound_head() call
with a call to page_folio().

Signed-off-by: Sidhartha Kumar <[e-mail]>
---
 mm/memory-failure.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

Comments

Matthew Wilcox July 15, 2023, 4:07 a.m. UTC | #1

On Thu, Jan 12, 2023 at 02:46:08PM -0600, Sidhartha Kumar wrote:
> @@ -2348,7 +2347,6 @@ int unpoison_memory(unsigned long pfn)
>  		return -ENXIO;
>  
>  	p = pfn_to_page(pfn);
> -	page = compound_head(p);
>  	folio = page_folio(p);
>  
>  	mutex_lock(&mf_mutex);
> @@ -2360,31 +2358,31 @@ int unpoison_memory(unsigned long pfn)
>  		goto unlock_mutex;
>  	}
>  
> -	if (!PageHWPoison(p)) {
> +	if (!folio_test_hwpoison(folio)) {

This is wrong.  You need to test the individual page for PageHWPoison()
instead of testing the folio.  I understand that this will work for
hugetlbfs pages, but for THP, it's the individual pages that get poisoned,
and folio_test_hwpoison() on a THP actually only tests the head page.

Ideas for preventing this mistake in the future gratefully received.

Patch

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index fb98652b211a..c53588ea5993 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2335,7 +2335,6 @@  core_initcall(memory_failure_init);
  */
 int unpoison_memory(unsigned long pfn)
 {
-	struct page *page;
 	struct folio *folio;
 	struct page *p;
 	int ret = -EBUSY;
@@ -2348,7 +2347,6 @@  int unpoison_memory(unsigned long pfn)
 		return -ENXIO;
 
 	p = pfn_to_page(pfn);
-	page = compound_head(p);
 	folio = page_folio(p);
 
 	mutex_lock(&mf_mutex);
@@ -2360,31 +2358,31 @@  int unpoison_memory(unsigned long pfn)
 		goto unlock_mutex;
 	}
 
-	if (!PageHWPoison(p)) {
+	if (!folio_test_hwpoison(folio)) {
 		unpoison_pr_info("Unpoison: Page was already unpoisoned %#lx\n",
 				 pfn, &unpoison_rs);
 		goto unlock_mutex;
 	}
 
-	if (page_count(page) > 1) {
+	if (folio_ref_count(folio) > 1) {
 		unpoison_pr_info("Unpoison: Someone grabs the hwpoison page %#lx\n",
 				 pfn, &unpoison_rs);
 		goto unlock_mutex;
 	}
 
-	if (page_mapped(page)) {
+	if (folio_mapped(folio)) {
 		unpoison_pr_info("Unpoison: Someone maps the hwpoison page %#lx\n",
 				 pfn, &unpoison_rs);
 		goto unlock_mutex;
 	}
 
-	if (page_mapping(page)) {
+	if (folio_mapping(folio)) {
 		unpoison_pr_info("Unpoison: the hwpoison page has non-NULL mapping %#lx\n",
 				 pfn, &unpoison_rs);
 		goto unlock_mutex;
 	}
 
-	if (PageSlab(page) || PageTable(page) || PageReserved(page))
+	if (folio_test_slab(folio) || PageTable(&folio->page) || folio_test_reserved(folio))
 		goto unlock_mutex;
 
 	ret = get_hwpoison_page(p, MF_UNPOISON);
@@ -2397,7 +2395,7 @@  int unpoison_memory(unsigned long pfn)
 				goto unlock_mutex;
 			}
 		}
-		ret = TestClearPageHWPoison(page) ? 0 : -EBUSY;
+		ret = folio_test_clear_hwpoison(folio) ? 0 : -EBUSY;
 	} else if (ret < 0) {
 		if (ret == -EHWPOISON) {
 			ret = put_page_back_buddy(p) ? 0 : -EBUSY;
@@ -2410,14 +2408,14 @@  int unpoison_memory(unsigned long pfn)
 			count = folio_free_raw_hwp(folio, false);
 			if (count == 0) {
 				ret = -EBUSY;
-				put_page(page);
+				folio_put(folio);
 				goto unlock_mutex;
 			}
 		}
 
-		put_page(page);
+		folio_put(folio);
 		if (TestClearPageHWPoison(p)) {
-			put_page(page);
+			folio_put(folio);
 			ret = 0;
 		}
 	}