From 5f17bdd2128998a3eeeb4521d136a192222fadb6 Mon Sep 17 00:00:00 2001
From: Kazuhito Hagio <k-hagio-ab@nec.com>
Date: Wed, 21 Dec 2022 11:06:39 +0900
Subject: [PATCH] [PATCH] Fix wrong exclusion of slab pages on Linux 6.2-rc1

* 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 wrongly 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@nec.com>
---
 makedumpfile.c | 6 +++---
 makedumpfile.h | 9 +++------
 2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/makedumpfile-1.7.2/makedumpfile.c b/makedumpfile-1.7.2/makedumpfile.c
index ff821eb..f403683 100644
--- a/makedumpfile-1.7.2/makedumpfile.c
+++ b/makedumpfile-1.7.2/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-1.7.2/makedumpfile.h b/makedumpfile-1.7.2/makedumpfile.h
index 70a1a91..21dec7d 100644
--- a/makedumpfile-1.7.2/makedumpfile.h
+++ b/makedumpfile-1.7.2/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())
-- 
2.39.0