+ memcg-enable-accounting-for-tty-related-objects.patch added to -mm tree

* + memcg-enable-accounting-for-tty-related-objects.patch added to -mm tree
@ 2021-07-27 21:08 akpm
  2021-07-28  6:08 ` Greg KH
  0 siblings, 1 reply; 3+ messages in thread
From: akpm @ 2021-07-27 21:08 UTC (permalink / raw)
  To: mm-commits, viro, vdavydov.dev, tj, tglx, shakeelb, serge, oleg,
	nglaive, mingo, mhocko, lizefan.x, ktkhai, jlayton, jirislaby,
	hpa, hannes, guro, gregkh, ebiederm, christian.brauner, bp, bp,
	bfields, axboe, avagin, adobriyan, 0x7f454c46, vvs


The patch titled
     Subject: memcg: enable accounting for tty-related objects
has been added to the -mm tree.  Its filename is
     memcg-enable-accounting-for-tty-related-objects.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/memcg-enable-accounting-for-tty-related-objects.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/memcg-enable-accounting-for-tty-related-objects.patch

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Vasily Averin <vvs@virtuozzo.com>
Subject: memcg: enable accounting for tty-related objects

At each login the user forces the kernel to create a new terminal and
allocate up to ~1Kb memory for the tty-related structures.

By default it's allowed to create up to 4096 ptys with 1024 reserve for
initial mount namespace only and the settings are controlled by host
admin.

Though this default is not enough for hosters with thousands of containers
per node.  Host admin can be forced to increase it up to NR_UNIX98_PTY_MAX
= 1<<20.

By default container is restricted by pty mount_opt.max = 1024, but admin
inside container can change it via remount.  As a result, one container
can consume almost all allowed ptys and allocate up to 1Gb of unaccounted
memory.

It is not enough per-se to trigger OOM on host, however anyway, it allows
to significantly exceed the assigned memcg limit and leads to troubles on
the over-committed node.

It makes sense to account for them to restrict the host's memory
consumption from inside the memcg-limited container.

Link: https://lkml.kernel.org/r/b8baa04f-e789-0321-b39d-07c5696ff755@virtuozzo.com
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Yutian Yang <nglaive@gmail.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/tty/tty_io.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/tty/tty_io.c~memcg-enable-accounting-for-tty-related-objects
+++ a/drivers/tty/tty_io.c
@@ -1493,7 +1493,7 @@ void tty_save_termios(struct tty_struct
 	/* Stash the termios data */
 	tp = tty->driver->termios[idx];
 	if (tp == NULL) {
-		tp = kmalloc(sizeof(*tp), GFP_KERNEL);
+		tp = kmalloc(sizeof(*tp), GFP_KERNEL_ACCOUNT);
 		if (tp == NULL)
 			return;
 		tty->driver->termios[idx] = tp;
@@ -3119,7 +3119,7 @@ struct tty_struct *alloc_tty_struct(stru
 {
 	struct tty_struct *tty;
 
-	tty = kzalloc(sizeof(*tty), GFP_KERNEL);
+	tty = kzalloc(sizeof(*tty), GFP_KERNEL_ACCOUNT);
 	if (!tty)
 		return NULL;
 
_

Patches currently in -mm which might be from vvs@virtuozzo.com are

memcg-enable-accounting-for-pids-in-nested-pid-namespaces.patch
memcg-enable-accounting-for-mnt_cache-entries.patch
memcg-enable-accounting-for-pollfd-and-select-bits-arrays.patch
memcg-enable-accounting-for-file-lock-caches.patch
memcg-enable-accounting-for-fasync_cache.patch
memcg-enable-accounting-for-new-namesapces-and-struct-nsproxy.patch
memcg-enable-accounting-of-ipc-resources.patch
memcg-enable-accounting-for-signals.patch
memcg-enable-accounting-for-posix_timers_cache-slab.patch
memcg-enable-accounting-for-tty-related-objects.patch
memcg-enable-accounting-for-ldt_struct-objects.patch


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