Thank you for the fix, Kazu.
On Tue, Jun 11, 2024 at 10:42 AM <devel-request@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Date: Tue, 11 Jun 2024 02:40:55 +0000
From: HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@xxxxxxx>
Subject: [PATCH] Fix "kmem -i" and "swap" commands on
Linux 6.10-rc1 and later kernels
To: "devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx"
<devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
Message-ID: <1718073652-13444-1-git-send-email-k-hagio-ab@xxxxxxx>
Content-Type: text/plain; charset="iso-2022-jp"
Kernel commit 798cb7f9aec3 ("swapon(2)/swapoff(2): don't bother with
block size") removed swap_info_struct.old_block_size member at Linux
6.10-rc1. The crash-utility has used this to determine whether a swap
is a partition or file and to determine the way to get the swap path.
Withtout the patch, the "kmem -i" and "swap" commands fail with the
following error messsage:
crash> kmem -i
...
TOTAL HUGE 13179392 50.3 GB ----
HUGE FREE 13179392 50.3 GB 100% of TOTAL HUGE
swap: invalid (optional) structure member offsets: swap_info_struct_swap_device or swap_info_struct_old_block_size
FILE: memory.c LINE: 16032 FUNCTION: dump_swap_info()
The swap_file member of recent swap_info_struct is a pointer to a
struct file (once upon a time it was dentry), use this fact directly.
Signed-off-by: Kazuhito Hagio <k-hagio-ab@xxxxxxx>
---
NOTE: This patch can be applied on top of my '[PATCH] Fix "kmem -v"
option on Linux 6.9 and later kernels' patch. Otherwise, please adjust
the hunk for offset_table.
defs.h | 1 +
filesys.c | 1 +
memory.c | 28 +++++++++++++++++++++++-----
symbols.c | 1 +
4 files changed, 26 insertions(+), 5 deletions(-)
diff --git a/defs.h b/defs.h
index 95de33188070..64bf785b7a1b 100644
--- a/defs.h
+++ b/defs.h
@@ -2242,6 +2242,7 @@ struct offset_table { /* stash of commonly-used offsets */
long log_caller_id;
long vmap_node_busy;
long rb_list_head;
+ long file_f_inode;
};
struct size_table { /* stash of commonly-used sizes */
diff --git a/filesys.c b/filesys.c
index 81fe856699e1..406ebb299780 100644
--- a/filesys.c
+++ b/filesys.c
@@ -2038,6 +2038,7 @@ vfs_init(void)
MEMBER_OFFSET_INIT(file_f_dentry, "file", "f_dentry");
MEMBER_OFFSET_INIT(file_f_vfsmnt, "file", "f_vfsmnt");
MEMBER_OFFSET_INIT(file_f_count, "file", "f_count");
+ MEMBER_OFFSET_INIT(file_f_inode, "file", "f_inode");
MEMBER_OFFSET_INIT(path_mnt, "path", "mnt");
MEMBER_OFFSET_INIT(path_dentry, "path", "dentry");
if (INVALID_MEMBER(file_f_dentry)) {
diff --git a/memory.c b/memory.c
index acb8507cfb75..28f901f16adf 100644
--- a/memory.c
+++ b/memory.c
@@ -16075,6 +16075,8 @@ dump_swap_info(ulong swapflags, ulong *totalswap_pages, ulong *totalused_pages)
char buf3[BUFSIZE];
char buf4[BUFSIZE];
char buf5[BUFSIZE];
+ int swap_file_is_file =
+ STREQ(MEMBER_TYPE_NAME("swap_info_struct", "swap_file"), "file");
This patch looks good, but I still have one question:
The 'swap_file' has been added into the struct swap_info_struct since linux v2.6.12-rc2, and until now it(its type) has been never changed, it indicates that the above checking is always true.
STREQ(MEMBER_TYPE_NAME("swap_info_struct", "swap_file"), "file")
Is that expected behavior? Just want to confirm with you.
Thanks
Lianbo
if (!symbol_exists("nr_swapfiles"))
error(FATAL, "nr_swapfiles doesn't exist in this kernel!\n");
@@ -16118,9 +16120,21 @@ dump_swap_info(ulong swapflags, ulong *totalswap_pages, ulong *totalused_pages)
swap_file = ULONG(vt->swap_info_struct +
OFFSET(swap_info_struct_swap_file));
- swap_device = INT(vt->swap_info_struct +
- OFFSET_OPTION(swap_info_struct_swap_device,
- swap_info_struct_old_block_size));
+ /* Linux 6.10 and later */
+ if (INVALID_MEMBER(swap_info_struct_swap_device) &&
+ INVALID_MEMBER(swap_info_struct_old_block_size) &&
+ swap_file_is_file) {
+ ulong inode;
+ ushort mode;
+ readmem(swap_file + OFFSET(file_f_inode), KVADDR, &inode,
+ sizeof(ulong), "swap_file.f_inode", FAULT_ON_ERROR);
+ readmem(inode + OFFSET(inode_i_mode), KVADDR, &mode,
+ sizeof(ushort), "inode.i_mode", FAULT_ON_ERROR);
+ swap_device = S_ISBLK(mode);
+ } else
+ swap_device = INT(vt->swap_info_struct +
+ OFFSET_OPTION(swap_info_struct_swap_device,
+ swap_info_struct_old_block_size));
pages = INT(vt->swap_info_struct +
OFFSET(swap_info_struct_pages));
@@ -16161,8 +16175,12 @@ dump_swap_info(ulong swapflags, ulong *totalswap_pages, ulong *totalused_pages)
OFFSET(swap_info_struct_swap_vfsmnt));
get_pathname(swap_file, buf, BUFSIZE,
1, vfsmnt);
- } else if (VALID_MEMBER
- (swap_info_struct_old_block_size)) {
+ } else if (VALID_MEMBER(swap_info_struct_old_block_size) ||
+ swap_file_is_file) {
+ /*
+ * Linux 6.10 and later kernels do not have old_block_size,
+ * but this still should work, if swap_file is file.
+ */
devname = vfsmount_devname(file_to_vfsmnt(swap_file),
buf1, BUFSIZE);
get_pathname(file_to_dentry(swap_file),
diff --git a/symbols.c b/symbols.c
index 283b98a8fbfe..0bf050ab62d0 100644
--- a/symbols.c
+++ b/symbols.c
@@ -10522,6 +10522,7 @@ dump_offset_table(char *spec, ulong makestruct)
OFFSET(file_f_count));
fprintf(fp, " file_f_path: %ld\n",
OFFSET(file_f_path));
+ fprintf(fp, " file_f_inode: %ld\n", OFFSET(file_f_inode));
fprintf(fp, " path_mnt: %ld\n",
OFFSET(path_mnt));
fprintf(fp, " path_dentry: %ld\n",
--
2.31.1
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