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

[Coiby Xu]

Resolves: bz2155754
Upstream: https://github.com/makedumpfile/makedumpfile
Conflict: None

commit 5f17bdd2128998a3eeeb4521d136a192222fadb6
Author: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt;
Date:   Wed Dec 21 11:06:39 2022 +0900

    [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(a)nec.com&gt;

Reported-by: Baoquan He <bhe(a)redhat.com&gt;
Signed-off-by: Coiby Xu <coxu(a)redhat.com&gt;
---
 ...exclusion-of-slab-pages-on-Linux-6.2.patch | 81 +++++++++++++++++++
 kexec-tools.spec                              |  2 +
 2 files changed, 83 insertions(+)
 create mode 100644
kexec-tools-2.0.26-makedumpfile-Fix-wrong-exclusion-of-slab-pages-on-Linux-6.2.patch

diff --git
a/kexec-tools-2.0.26-makedumpfile-Fix-wrong-exclusion-of-slab-pages-on-Linux-6.2.patch
b/kexec-tools-2.0.26-makedumpfile-Fix-wrong-exclusion-of-slab-pages-on-Linux-6.2.patch
new file mode 100644
index 00000000..5d91bc21
--- /dev/null
+++
b/kexec-tools-2.0.26-makedumpfile-Fix-wrong-exclusion-of-slab-pages-on-Linux-6.2.patch
@@ -0,0 +1,81 @@
+From 5f17bdd2128998a3eeeb4521d136a192222fadb6 Mon Sep 17 00:00:00 2001
+From: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt;
+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(a)nec.com&gt;
+---
+ 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
+
diff --git a/kexec-tools.spec b/kexec-tools.spec
index ea49eb2c..33656dc4 100644
--- a/kexec-tools.spec
+++ b/kexec-tools.spec
@@ -105,6 +105,7 @@ Requires:       systemd-udev%{?_isa}
 #
 # Patches 601 onward are generic patches
 #
+Patch601:
kexec-tools-2.0.26-makedumpfile-Fix-wrong-exclusion-of-slab-pages-on-Linux-6.2.patch
 
 %description
 kexec-tools provides /sbin/kexec binary that facilitates a new
@@ -120,6 +121,7 @@ mkdir -p -m755 kcp
 tar -z -x -v -f %{SOURCE9}
 tar -z -x -v -f %{SOURCE19}
 
+%patch601 -p1
 
 %ifarch ppc
 %define archdef ARCH=ppc
-- 
2.39.0