>>>> (gdb) p nr_swapper_spaces
>>>> $4 = <optimized out>
>>> Thank you folks, for the various information.
>>>
>>> Apparently the data of nr_swapper_spaces exists in the kernel, but its
>>> symbol does not exist. I think this means that we cannot calculate the
>>> number of pages from swapper_spaces[] with such a debuginfo, because we
>>> cannot get the array size of a swapper_spaces entry.
>>
>> That's correct, Kazu.
>>
>>
>>> So I'd like to go with Johan's patch.
>>>
>>> cc -c -g -DX86_64 -DLZO -DSNAPPY -DGDB_10_2 memory.c -Wall -O2
>>> -Wstrict-prototypes -Wmissing-prototypes -fstack-protector
>>> -Wformat-security
>>> memory.c: In function dump_kmeminfo:
>>> memory.c:8612:50: warning: pointer targets in passing argument 2 of
>>> dump_vm_stat differ in signedness [-Wpointer-sign]
>>> 8612 | if (dump_vm_stat("NR_SWAPCACHE",
>>> &swapper_space_nrpages, 0)) {
>>> |
>>> ^~~~~~~~~~~~~~~~~~~~~~
>>> | |
>>> | ulong * {aka
>>> long unsigned int *}
>>> memory.c:298:33: note: expected long int * but argument is of type ulong
>>> * {aka long unsigned int *}
>>> 298 | static int dump_vm_stat(char *, long *, ulong);
>>> | ^~~~~~
>>>
>>> So with the following,
>>>
>>> - ulong swapper_space_nrpages;
>>> + long swapper_space_nrpages;
>>
>> Looks good. Maybe the patch log also needs to be improved a little bit.
>>
>> Although the checking of kernel version looks not very good, seems no
>> better way.
>
>hmm, this sounds strange. My ack is for Johan's patch (attached), which
>does not have kernel version check, is this ok? sorry for confusing.
>
>Johan, your patch does not have your Signed-off-by tag, could I have it?
Sure, attaching it with Signed-off-by tag.
Thanks for looking into it.
JohanFrom de17832e73a53e0d069099cb085b93bb02d6db70 Mon Sep 17 00:00:00 2001
From: Johan Erlandsson <johan.erlandsson@xxxxxxxx>
Date: Wed, 19 Apr 2023 11:26:04 +0200
Subject: [PATCH] read swapcache usage when nr_swapper_spaces isn't available
In 5.12 the following change was introduced:
b6038942480e574c697ea1a80019bbe586c1d654
Then the variable 'nr_swapper_spaces' is not read (unless
CONFIG_DEBUG_VM=y). In GKI builds this variable is then optimized
out. But the same change provided a new way to obtain the same
information, using NR_SWAPCACHE.
Signed-off-by: Johan Erlandsson <johan.erlandsson@xxxxxxxx>
---
memory.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/memory.c b/memory.c
index 791194a..439e6e3 100644
--- a/memory.c
+++ b/memory.c
@@ -8609,7 +8609,8 @@ dump_kmeminfo(void)
char *swapper_space = GETBUF(SIZE(address_space));
swapper_space_nrpages = 0;
- if (symbol_exists("nr_swapper_spaces") &&
+ if (dump_vm_stat("NR_SWAPCACHE", &swapper_space_nrpages, 0)) {
+ } else if (symbol_exists("nr_swapper_spaces") &&
(len = get_array_length("nr_swapper_spaces",
NULL, 0))) {
char *nr_swapper_space =
--
2.42.0
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