From: Vasilis Liaskovitis <vliaskovitis@suse.com>
To: util-linux@vger.kernel.org
Cc: ruediger.meier@ga-group.nl, sbrabec@suse.com
Subject: [PATCH] ipcs: Avoid shmall overflows
Date: Wed, 16 Dec 2020 15:54:29 +0100 [thread overview]
Message-ID: <aa7c757636594db8f122185293393e326652e53d.camel@suse.com> (raw)
Avoid computing the number of bytes in shmall, by only
computing the number of Kbytes. This improves some
overflows, e.g.
$ echo "4503599627370496" > /proc/sys/kernel/shmall
$ ipcs -l | grep 'max total shared memory'
Before:
max total shared memory (kbytes) = 18014398509481980
After:
max total shared memory (kbytes) = 18014398509481984
$ echo "99993599627370500" > /proc/sys/kernel/shmall
99993599627370500
$ ipcs -l | grep 'max total shared memory'
Before:
max total shared memory (kbytes) = 18014398509481980
After:
max total shared memory (kbytes) = 399974398509482000
Signed-off-by: Vasilis Liaskovitis <vliaskovitis@suse.com>
---
sys-utils/ipcs.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/sys-utils/ipcs.c b/sys-utils/ipcs.c
index fc6fba4a6..544a3adcc 100644
--- a/sys-utils/ipcs.c
+++ b/sys-utils/ipcs.c
@@ -216,13 +216,9 @@ static void do_shm (char format, int unit)
ipc_print_size(unit == IPC_UNIT_DEFAULT ? IPC_UNIT_KB :
unit,
_("max seg size"), lim.shmmax, "\n", 0);
- tmp = (uint64_t) lim.shmall * pgsz;
- /* overflow handling, at least we don't print
ridiculous small values */
- if (lim.shmall != 0 && tmp / lim.shmall != pgsz) {
- tmp = UINT64_MAX - (UINT64_MAX % pgsz);
- }
- ipc_print_size(unit == IPC_UNIT_DEFAULT ? IPC_UNIT_KB :
unit,
- _("max total shared memory"), tmp, "\n",
0);
+ ipc_print_size(IPC_UNIT_DEFAULT,
+ _("max total shared memory (kbytes)"),
(pgsz / 1024) *
+ (uint64_t) lim.shmall, "\n", 0);
ipc_print_size(unit == IPC_UNIT_DEFAULT ?
IPC_UNIT_BYTES : unit,
_("min seg size"), lim.shmmin, "\n", 0);
return;
--
2.28.0
next reply other threads:[~2020-12-16 14:56 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-16 14:54 Vasilis Liaskovitis [this message]
2021-01-04 12:20 ` [PATCH] ipcs: Avoid shmall overflows Karel Zak
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