[PATCH makedumpfile] Fix incorrect exclusion of slab pages on Linux 6.2-rc1

[HAGIO KAZUHITO(萩尾 一仁)]

From: Kazuhito Hagio <k-hagio-ab at nec.com>

* Required for kernel 6.2

Kernel commit 130d4df57390 ("mm/sl[au]b: rearrange struct slab fields to
allow larger rcu_head"), which is contained in Linux 6.2-rc1 and later,
made the offset of slab.slabs equal to page.mapping's one.  As a result,
"makedumpfile -d 8", which should exclude user data, excludes some slab
pages incorrectly because isAnon() returns true when slab.slabs is an
odd number.  With such dumpfiles, crash can fail to start session with
an error like this:

  # crash vmlinux dumpfile
  ...
  crash: page excluded: kernel virtual address: ffff8fa047ac2fe8 type: "xa_node shift"

Make isAnon() check that the page is not slab to fix this.

Signed-off-by: Kazuhito Hagio <k-hagio-ab at nec.com>
---
 makedumpfile.c | 6 +++---
 makedumpfile.h | 9 +++------
 2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index ff821ebd3eb0..f40368364cf3 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -6502,7 +6502,7 @@ __exclude_unnecessary_pages(unsigned long mem_map,
 		 */
 		else if ((info->dump_level & DL_EXCLUDE_CACHE)
 		    && is_cache_page(flags)
-		    && !isPrivate(flags) && !isAnon(mapping)) {
+		    && !isPrivate(flags) && !isAnon(mapping, flags)) {
 			pfn_counter = &pfn_cache;
 		}
 		/*
@@ -6510,7 +6510,7 @@ __exclude_unnecessary_pages(unsigned long mem_map,
 		 */
 		else if ((info->dump_level & DL_EXCLUDE_CACHE_PRI)
 		    && is_cache_page(flags)
-		    && !isAnon(mapping)) {
+		    && !isAnon(mapping, flags)) {
 			if (isPrivate(flags))
 				pfn_counter = &pfn_cache_private;
 			else
@@ -6522,7 +6522,7 @@ __exclude_unnecessary_pages(unsigned long mem_map,
 		 *  - hugetlbfs pages
 		 */
 		else if ((info->dump_level & DL_EXCLUDE_USER_DATA)
-			 && (isAnon(mapping) || isHugetlb(compound_dtor))) {
+			 && (isAnon(mapping, flags) || isHugetlb(compound_dtor))) {
 			pfn_counter = &pfn_user;
 		}
 		/*
diff --git a/makedumpfile.h b/makedumpfile.h
index 70a1a91d66be..21dec7d1145c 100644
--- a/makedumpfile.h
+++ b/makedumpfile.h
@@ -161,12 +161,9 @@ test_bit(int nr, unsigned long addr)
 #define isSwapBacked(flags)	test_bit(NUMBER(PG_swapbacked), flags)
 #define isHWPOISON(flags)	(test_bit(NUMBER(PG_hwpoison), flags) \
 				&& (NUMBER(PG_hwpoison) != NOT_FOUND_NUMBER))
-
-static inline int
-isAnon(unsigned long mapping)
-{
-	return ((unsigned long)mapping & PAGE_MAPPING_ANON) != 0;
-}
+#define isSlab(flags)		test_bit(NUMBER(PG_slab), flags)
+#define isAnon(mapping, flags)	(((unsigned long)mapping & PAGE_MAPPING_ANON) != 0 \
+				&& !isSlab(flags))
 
 #define PTOB(X)			(((unsigned long long)(X)) << PAGESHIFT())
 #define BTOP(X)			(((unsigned long long)(X)) >> PAGESHIFT())
-- 
2.31.1