2:12 a.m.
From: Kazuhito Hagio <k-hagio-ab(a)nec.com>
Kernel commit 8578e0c00dcf ("mm, swap: use the swap table to track the
swap count"), which is contained in Linux 6.18 and later kernels,
removed swapper_spaces symbol.
As a result, "kmem -i" skips swap usage output because the existing
check only looks for swapper_space/swapper_spaces.
Also check for the swap_info symbol so dump_swap_info() is called on
newer kernels as well.
Signed-off-by: Kazuhito Hagko <k-hagio-ab(a)nec.com>
---
memory.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/memory.c b/memory.c
index 38c6a139e984..15946c58eaf2 100644
--- a/memory.c
+++ b/memory.c
@@ -8871,7 +8871,8 @@ dump_kmeminfo(struct meminfo *mi)
* get swap data from dump_swap_info().
*/
fprintf(fp, "\n");
- if (symbol_exists("swapper_space") ||
symbol_exists("swapper_spaces")) {
+ if (symbol_exists("swap_info") ||
+ symbol_exists("swapper_space") ||
symbol_exists("swapper_spaces")) {
if (dump_swap_info(RETURN_ON_ERROR, &totalswap_pages,
&totalused_pages)) {
fprintf(fp, "%13s %7ld %11s ----\n",
--
2.31.1
2:12 a.m.
New subject: [PATCH 2/2] Fix "swap" command on Linux 7.1 and later
From: Kazuhito Hagio <k-hagio-ab(a)nec.com>
Kernel commit 0d6af9bcf383 ("mm, swap: use the swap table to track the
swap count"), which is contained in Linux 7.1 and later kernels, removed
swap_info_struct.swap_map member.
As a result, the "swap" command and "kmem -i" option fail with the
following error:
swap: invalid structure member offset: swap_info_struct_swap_map
FILE: memory.c LINE: 16293 FUNCTION: dump_swap_info()
Fix it by referencing swap_info_struct.swap_map only for SWAPINFO_V1,
where it is actually needed. Newer kernels no longer have that member,
and the command can use the existing inuse_pages handling instead.
Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
---
memory.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/memory.c b/memory.c
index 15946c58eaf2..3f3aa274ab5a 100644
--- a/memory.c
+++ b/memory.c
@@ -16290,9 +16290,6 @@ dump_swap_info(ulong swapflags, ulong *totalswap_pages, ulong
*totalused_pages)
OFFSET(swap_info_struct_inuse_pages));
}
- swap_map = ULONG(vt->swap_info_struct +
- OFFSET(swap_info_struct_swap_map));
-
if (swap_file) {
if (VALID_MEMBER(swap_info_struct_swap_vfsmnt)) {
vfsmnt = ULONG(vt->swap_info_struct +
@@ -16322,6 +16319,9 @@ dump_swap_info(ulong swapflags, ulong *totalswap_pages, ulong
*totalused_pages)
if (vt->flags & SWAPINFO_V1) {
smap = (ushort *)GETBUF(sizeof(ushort) * max);
+ swap_map = ULONG(vt->swap_info_struct +
+ OFFSET(swap_info_struct_swap_map));
+
if (!readmem(swap_map, KVADDR, smap,
sizeof(ushort) * max, "swap_info swap_map data",
RETURN_ON_ERROR|QUIET)) {
--
2.31.1
2:29 a.m.
New subject: [PATCH 2/2] Fix "swap" command on Linux 7.1 and later
Hi Kazu,
Thanks for the fix. I'm OK with patch 1 & 2, ack.
Thanks,
Tao Liu
On Wed, Jun 3, 2026 at 7:14 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab(a)nec.com> wrote:
From: Kazuhito Hagio <k-hagio-ab(a)nec.com>
Kernel commit 0d6af9bcf383 ("mm, swap: use the swap table to track the
swap count"), which is contained in Linux 7.1 and later kernels, removed
swap_info_struct.swap_map member.
As a result, the "swap" command and "kmem -i" option fail with the
following error:
swap: invalid structure member offset: swap_info_struct_swap_map
FILE: memory.c LINE: 16293 FUNCTION: dump_swap_info()
Fix it by referencing swap_info_struct.swap_map only for SWAPINFO_V1,
where it is actually needed. Newer kernels no longer have that member,
and the command can use the existing inuse_pages handling instead.
Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
---
memory.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/memory.c b/memory.c
index 15946c58eaf2..3f3aa274ab5a 100644
--- a/memory.c
+++ b/memory.c
@@ -16290,9 +16290,6 @@ dump_swap_info(ulong swapflags, ulong *totalswap_pages, ulong
*totalused_pages)
OFFSET(swap_info_struct_inuse_pages));
}
- swap_map = ULONG(vt->swap_info_struct +
- OFFSET(swap_info_struct_swap_map));
-
if (swap_file) {
if (VALID_MEMBER(swap_info_struct_swap_vfsmnt)) {
vfsmnt = ULONG(vt->swap_info_struct +
@@ -16322,6 +16319,9 @@ dump_swap_info(ulong swapflags, ulong *totalswap_pages, ulong
*totalused_pages)
if (vt->flags & SWAPINFO_V1) {
smap = (ushort *)GETBUF(sizeof(ushort) * max);
+ swap_map = ULONG(vt->swap_info_struct +
+ OFFSET(swap_info_struct_swap_map));
+
if (!readmem(swap_map, KVADDR, smap,
sizeof(ushort) * max, "swap_info swap_map data",
RETURN_ON_ERROR|QUIET)) {
--
2.31.1
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2:34 a.m.
New subject: [PATCH 2/2] Fix "swap" command on Linux 7.1 and later
applied:
https://github.com/crash-utility/crash/commit/fdb94ed20ac85e8354224b0d691...
&
https://github.com/crash-utility/crash/commit/c894f05d3cdc5d3e61775c3f67b...
On Thu, Jun 4, 2026 at 7:29 PM Tao Liu <ltao(a)redhat.com> wrote:
Hi Kazu,
Thanks for the fix. I'm OK with patch 1 & 2, ack.
Thanks,
Tao Liu
On Wed, Jun 3, 2026 at 7:14 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab(a)nec.com> wrote:
>
> From: Kazuhito Hagio <k-hagio-ab(a)nec.com>
>
> Kernel commit 0d6af9bcf383 ("mm, swap: use the swap table to track the
> swap count"), which is contained in Linux 7.1 and later kernels, removed
> swap_info_struct.swap_map member.
>
> As a result, the "swap" command and "kmem -i" option fail with
the
> following error:
>
> swap: invalid structure member offset: swap_info_struct_swap_map
> FILE: memory.c LINE: 16293 FUNCTION: dump_swap_info()
>
> Fix it by referencing swap_info_struct.swap_map only for SWAPINFO_V1,
> where it is actually needed. Newer kernels no longer have that member,
> and the command can use the existing inuse_pages handling instead.
>
> Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
> ---
> memory.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/memory.c b/memory.c
> index 15946c58eaf2..3f3aa274ab5a 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -16290,9 +16290,6 @@ dump_swap_info(ulong swapflags, ulong *totalswap_pages,
ulong *totalused_pages)
> OFFSET(swap_info_struct_inuse_pages));
> }
>
> - swap_map = ULONG(vt->swap_info_struct +
> - OFFSET(swap_info_struct_swap_map));
> -
> if (swap_file) {
> if (VALID_MEMBER(swap_info_struct_swap_vfsmnt)) {
> vfsmnt = ULONG(vt->swap_info_struct +
> @@ -16322,6 +16319,9 @@ dump_swap_info(ulong swapflags, ulong *totalswap_pages,
ulong *totalused_pages)
> if (vt->flags & SWAPINFO_V1) {
> smap = (ushort *)GETBUF(sizeof(ushort) * max);
>
> + swap_map = ULONG(vt->swap_info_struct +
> + OFFSET(swap_info_struct_swap_map));
> +
> if (!readmem(swap_map, KVADDR, smap,
> sizeof(ushort) * max, "swap_info swap_map
data",
> RETURN_ON_ERROR|QUIET)) {
> --
> 2.31.1
> --
> Crash-utility mailing list -- devel(a)lists.crash-utility.osci.io
> To unsubscribe send an email to devel-leave(a)lists.crash-utility.osci.io
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>
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3 comments
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participants (2)
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HAGIO KAZUHITO(萩尾 一仁) -
Tao Liu