5.10-stable patches

added patches:
	ipc-remove-memcg-accounting-for-sops-objects-in-do_semtimedop.patch

diff --git a/queue-5.10/ipc-remove-memcg-accounting-for-sops-objects-in-do_semtimedop.patch b/queue-5.10/ipc-remove-memcg-accounting-for-sops-objects-in-do_semtimedop.patch
new file mode 100644 (file)
index 0000000..dc57fc6
--- /dev/null
+++ b/queue-5.10/ipc-remove-memcg-accounting-for-sops-objects-in-do_semtimedop.patch
@@ -0,0 +1,58 @@
+From 6a4746ba06191e23d30230738e94334b26590a8a Mon Sep 17 00:00:00 2001
+From: Vasily Averin <vvs@virtuozzo.com>
+Date: Sat, 11 Sep 2021 10:40:08 +0300
+Subject: ipc: remove memcg accounting for sops objects in do_semtimedop()
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Vasily Averin <vvs@virtuozzo.com>
+
+commit 6a4746ba06191e23d30230738e94334b26590a8a upstream.
+
+Linus proposes to revert an accounting for sops objects in
+do_semtimedop() because it's really just a temporary buffer
+for a single semtimedop() system call.
+
+This object can consume up to 2 pages, syscall is sleeping
+one, size and duration can be controlled by user, and this
+allocation can be repeated by many thread at the same time.
+
+However Shakeel Butt pointed that there are much more popular
+objects with the same life time and similar memory
+consumption, the accounting of which was decided to be
+rejected for performance reasons.
+
+Considering at least 2 pages for task_struct and 2 pages for
+the kernel stack, a back of the envelope calculation gives a
+footprint amplification of <1.5 so this temporal buffer can be
+safely ignored.
+
+The factor would IMO be interesting if it was >> 2 (from the
+PoV of excessive (ab)use, fine-grained accounting seems to be
+currently unfeasible due to performance impact).
+
+Link: https://lore.kernel.org/lkml/90e254df-0dfe-f080-011e-b7c53ee7fd20@virtuozzo.com/
+Fixes: 18319498fdd4 ("memcg: enable accounting of ipc resources")
+Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
+Acked-by: Michal Hocko <mhocko@suse.com>
+Reviewed-by: Michal Koutný <mkoutny@suse.com>
+Acked-by: Shakeel Butt <shakeelb@google.com>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ ipc/sem.c |    3 +--
+ 1 file changed, 1 insertion(+), 2 deletions(-)
+
+--- a/ipc/sem.c
++++ b/ipc/sem.c
+@@ -2001,8 +2001,7 @@ static long do_semtimedop(int semid, str
+       if (nsops > ns->sc_semopm)
+               return -E2BIG;
+       if (nsops > SEMOPM_FAST) {
+-              sops = kvmalloc_array(nsops, sizeof(*sops),
+-                                    GFP_KERNEL_ACCOUNT);
++              sops = kvmalloc_array(nsops, sizeof(*sops), GFP_KERNEL);
+               if (sops == NULL)
+                       return -ENOMEM;
+       }

diff --git a/queue-5.10/series b/queue-5.10/series
index 6ccbd8f6f8c008119d1db7931bbd69404c114ef7..0eacaffaa4f9b9645c91253a3aab2131944c9f70 100644 (file)
--- a/queue-5.10/series
+++ b/queue-5.10/series
@@ -115,3 +115,4 @@ drm-rockchip-dsi-force-synchronous-probe.patch
 drm-i915-sdvo-filter-out-invalid-outputs-more-sensibly.patch
 drm-i915-sdvo-setup-ddc-fully-before-output-init.patch
 wifi-brcmfmac-fix-potential-buffer-overflow-in-brcmf_fweh_event_worker.patch
+ipc-remove-memcg-accounting-for-sops-objects-in-do_semtimedop.patch