1:06 a.m.
On 2024/06/12 13:55, lijiang wrote:
Thank you for the fix, Kazu.
On Tue, Jun 11, 2024 at 10:42 AM <devel-request(a)lists.crash-utility.osci.io
<mailto:devel-request@lists.crash-utility.osci.io>> wrote:
Date: Tue, 11 Jun 2024 02:40:55 +0000
From: HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab(a)nec.com
<mailto:k-hagio-ab@nec.com>>
Subject: [Crash-utility] [PATCH] Fix "kmem -i" and "swap"
commands on
Linux 6.10-rc1 and later kernels
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<mailto:1718073652-13444-1-git-send-email-k-hagio-ab@nec.com>>
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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(a)nec.com
<mailto:k-hagio-ab@nec.com>>
---
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.
Yes.
As far as I checked, swap_file was changed from 'dentry *' to 'file *'
at somewhere between v2.4.0 and v2.6.0, so not always true.
get_pathname()'s first arg is dentry, we have to choose the else-if block
without old_block_size, so I decided to use its type information directly
} else if (VALID_MEMBER(swap_info_struct_old_block_size) ||
swap_file_is_file) {
The other if / else blocks are for very old kernels, so maybe they won't
be used, but if we don't remove these, I think this is a reasonable way.
Does this answer your question?
Thanks,
Kazu
>
> 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
>