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linux 6.0.y: misc-additions: Add mm: vmscan: fix extreme overreclaim and swap floods and Bluetooth: fix deadlock for RFCOMM sk state change cherry picks from Arch

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Wifi issues were fixed with 6.0.2, thankfully
This commit is contained in:
Tk-Glitch
2022-10-15 15:05:21 +02:00
parent e801f7735b
commit 2a07409439
2 changed files with 363 additions and 1 deletions
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2
PKGBUILD
View File

@@ -56,7 +56,7 @@ else
fi
pkgname=("${pkgbase}" "${pkgbase}-headers")
pkgver="${_basekernel}"."${_sub}"
pkgrel=270
pkgrel=271
pkgdesc='Linux-tkg'
arch=('x86_64') # no i686 in here
url="https://www.kernel.org/"

362
linux-tkg-patches/6.0/0012-misc-additions.patch
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@@ -64,3 +64,365 @@ index 2c7171e0b0010..85de313ddec29 100644
select CPU_FREQ_GOV_PERFORMANCE
help
From 2535fbde890f14c78b750139fcf87d1143850626 Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@cmpxchg.org>
Date: Tue, 2 Aug 2022 12:28:11 -0400
Subject: [PATCH] mm: vmscan: fix extreme overreclaim and swap floods
During proactive reclaim, we sometimes observe severe overreclaim, with
several thousand times more pages reclaimed than requested.
This trace was obtained from shrink_lruvec() during such an instance:
prio:0 anon_cost:1141521 file_cost:7767
nr_reclaimed:4387406 nr_to_reclaim:1047 (or_factor:4190)
nr=[7161123 345 578 1111]
While he reclaimer requested 4M, vmscan reclaimed close to 16G, most of it
by swapping. These requests take over a minute, during which the write()
to memory.reclaim is unkillably stuck inside the kernel.
Digging into the source, this is caused by the proportional reclaim
bailout logic. This code tries to resolve a fundamental conflict: to
reclaim roughly what was requested, while also aging all LRUs fairly and
in accordance to their size, swappiness, refault rates etc. The way it
attempts fairness is that once the reclaim goal has been reached, it stops
scanning the LRUs with the smaller remaining scan targets, and adjusts the
remainder of the bigger LRUs according to how much of the smaller LRUs was
scanned. It then finishes scanning that remainder regardless of the
reclaim goal.
This works fine if priority levels are low and the LRU lists are
comparable in size. However, in this instance, the cgroup that is
targeted by proactive reclaim has almost no files left - they've already
been squeezed out by proactive reclaim earlier - and the remaining anon
pages are hot. Anon rotations cause the priority level to drop to 0,
which results in reclaim targeting all of anon (a lot) and all of file
(almost nothing). By the time reclaim decides to bail, it has scanned
most or all of the file target, and therefor must also scan most or all of
the enormous anon target. This target is thousands of times larger than
the reclaim goal, thus causing the overreclaim.
The bailout code hasn't changed in years, why is this failing now? The
most likely explanations are two other recent changes in anon reclaim:
1. Before the series starting with commit 5df741963d52 ("mm: fix LRU
balancing effect of new transparent huge pages"), the VM was
overall relatively reluctant to swap at all, even if swap was
configured. This means the LRU balancing code didn't come into play
as often as it does now, and mostly in high pressure situations
where pronounced swap activity wouldn't be as surprising.
2. For historic reasons, shrink_lruvec() loops on the scan targets of
all LRU lists except the active anon one, meaning it would bail if
the only remaining pages to scan were active anon - even if there
were a lot of them.
Before the series starting with commit ccc5dc67340c ("mm/vmscan:
make active/inactive ratio as 1:1 for anon lru"), most anon pages
would live on the active LRU; the inactive one would contain only a
handful of preselected reclaim candidates. After the series, anon
gets aged similarly to file, and the inactive list is the default
for new anon pages as well, making it often the much bigger list.
As a result, the VM is now more likely to actually finish large
anon targets than before.
Change the code such that only one SWAP_CLUSTER_MAX-sized nudge toward the
larger LRU lists is made before bailing out on a met reclaim goal.
This fixes the extreme overreclaim problem.
Fairness is more subtle and harder to evaluate. No obvious misbehavior
was observed on the test workload, in any case. Conceptually, fairness
should primarily be a cumulative effect from regular, lower priority
scans. Once the VM is in trouble and needs to escalate scan targets to
make forward progress, fairness needs to take a backseat. This is also
acknowledged by the myriad exceptions in get_scan_count(). This patch
makes fairness decrease gradually, as it keeps fairness work static over
increasing priority levels with growing scan targets. This should make
more sense - although we may have to re-visit the exact values.
Link: https://lkml.kernel.org/r/20220802162811.39216-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/vmscan.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 382dbe97329f33..266eb8cfe93a67 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2955,8 +2955,8 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
enum lru_list lru;
unsigned long nr_reclaimed = 0;
unsigned long nr_to_reclaim = sc->nr_to_reclaim;
+ bool proportional_reclaim;
struct blk_plug plug;
- bool scan_adjusted;
get_scan_count(lruvec, sc, nr);
@@ -2974,8 +2974,8 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
* abort proportional reclaim if either the file or anon lru has already
* dropped to zero at the first pass.
*/
- scan_adjusted = (!cgroup_reclaim(sc) && !current_is_kswapd() &&
- sc->priority == DEF_PRIORITY);
+ proportional_reclaim = (!cgroup_reclaim(sc) && !current_is_kswapd() &&
+ sc->priority == DEF_PRIORITY);
blk_start_plug(&plug);
while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
@@ -2995,7 +2995,7 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
cond_resched();
- if (nr_reclaimed < nr_to_reclaim || scan_adjusted)
+ if (nr_reclaimed < nr_to_reclaim || proportional_reclaim)
continue;
/*
@@ -3046,8 +3046,6 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
nr_scanned = targets[lru] - nr[lru];
nr[lru] = targets[lru] * (100 - percentage) / 100;
nr[lru] -= min(nr[lru], nr_scanned);
-
- scan_adjusted = true;
}
blk_finish_plug(&plug);
sc->nr_reclaimed += nr_reclaimed;
From 430daaab3c78de6bd82f10cfb5a0f016c6e583f6 Mon Sep 17 00:00:00 2001
From: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Date: Mon, 4 Oct 2021 14:07:34 -0400
Subject: [PATCH] Bluetooth: fix deadlock for RFCOMM sk state change
Syzbot reports the following task hang [1]:
INFO: task syz-executor255:8499 blocked for more than 143 seconds.
Not tainted 5.14.0-rc7-syzkaller #0
Call Trace:
context_switch kernel/sched/core.c:4681 [inline]
__schedule+0x93a/0x26f0 kernel/sched/core.c:5938
schedule+0xd3/0x270 kernel/sched/core.c:6017
__lock_sock+0x13d/0x260 net/core/sock.c:2644
lock_sock_nested+0xf6/0x120 net/core/sock.c:3185
lock_sock include/net/sock.h:1612 [inline]
rfcomm_sk_state_change+0xb4/0x390 net/bluetooth/rfcomm/sock.c:73
__rfcomm_dlc_close+0x1b6/0x8a0 net/bluetooth/rfcomm/core.c:489
rfcomm_dlc_close+0x1ea/0x240 net/bluetooth/rfcomm/core.c:520
__rfcomm_sock_close+0xac/0x260 net/bluetooth/rfcomm/sock.c:220
rfcomm_sock_shutdown+0xe9/0x210 net/bluetooth/rfcomm/sock.c:931
rfcomm_sock_release+0x5f/0x140 net/bluetooth/rfcomm/sock.c:951
__sock_release+0xcd/0x280 net/socket.c:649
sock_close+0x18/0x20 net/socket.c:1314
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xdd/0x1a0 kernel/task_work.c:164
exit_task_work include/linux/task_work.h:32 [inline]
do_exit+0xbd4/0x2a60 kernel/exit.c:825
do_group_exit+0x125/0x310 kernel/exit.c:922
get_signal+0x47f/0x2160 kernel/signal.c:2808
arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
handle_signal_work kernel/entry/common.c:148 [inline]
exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae
Showing all locks held in the system:
1 lock held by khungtaskd/1653:
#0: ffffffff8b97c280 (rcu_read_lock){....}-{1:2}, at:
debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6446
1 lock held by krfcommd/4781:
#0: ffffffff8d306528 (rfcomm_mutex){+.+.}-{3:3}, at:
rfcomm_process_sessions net/bluetooth/rfcomm/core.c:1979 [inline]
#0: ffffffff8d306528 (rfcomm_mutex){+.+.}-{3:3}, at:
rfcomm_run+0x2ed/0x4a20 net/bluetooth/rfcomm/core.c:2086
2 locks held by in:imklog/8206:
#0: ffff8880182ce5f0 (&f->f_pos_lock){+.+.}-{3:3}, at:
__fdget_pos+0xe9/0x100 fs/file.c:974
#1: ffff8880b9c51a58 (&rq->__lock){-.-.}-{2:2}, at:
raw_spin_rq_lock_nested kernel/sched/core.c:460 [inline]
#1: ffff8880b9c51a58 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock
kernel/sched/sched.h:1307 [inline]
#1: ffff8880b9c51a58 (&rq->__lock){-.-.}-{2:2}, at: rq_lock
kernel/sched/sched.h:1610 [inline]
#1: ffff8880b9c51a58 (&rq->__lock){-.-.}-{2:2}, at:
__schedule+0x233/0x26f0 kernel/sched/core.c:5852
4 locks held by syz-executor255/8499:
#0: ffff888039a83690 (&sb->s_type->i_mutex_key#13){+.+.}-{3:3}, at:
inode_lock include/linux/fs.h:774 [inline]
#0: ffff888039a83690 (&sb->s_type->i_mutex_key#13){+.+.}-{3:3}, at:
__sock_release+0x86/0x280 net/socket.c:648
#1:
ffff88802fa31120 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0},
at: lock_sock include/net/sock.h:1612 [inline]
#1:
ffff88802fa31120 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0},
at: rfcomm_sock_shutdown+0x54/0x210 net/bluetooth/rfcomm/sock.c:928
#2: ffffffff8d306528 (rfcomm_mutex){+.+.}-{3:3}, at:
rfcomm_dlc_close+0x34/0x240 net/bluetooth/rfcomm/core.c:507
#3: ffff888141bd6d28 (&d->lock){+.+.}-{3:3}, at:
__rfcomm_dlc_close+0x162/0x8a0 net/bluetooth/rfcomm/core.c:487
==================================================================
The task hangs because of a deadlock that occurs when lock_sock() is
called in rfcomm_sk_state_change(). One such call stack is:
rfcomm_sock_shutdown():
lock_sock();
__rfcomm_sock_close():
rfcomm_dlc_close():
__rfcomm_dlc_close():
rfcomm_dlc_lock();
rfcomm_sk_state_change():
lock_sock();
lock_sock() has to be called when the sk state is changed because the
lock is not always held when rfcomm_sk_state_change() is
called. However, besides the recursive deadlock, there is also an
issue of a lock hierarchy inversion between rfcomm_dlc_lock() and
lock_sock() if the socket is locked in rfcomm_sk_state_change().
To avoid these issues, we can instead schedule the sk state change in
the global workqueue. This is already the implicit assumption about
how sk state changes happen. For example, in rfcomm_sock_shutdown(),
the call to __rfcomm_sock_close() is followed by
bt_sock_wait_state().
Additionally, the call to rfcomm_sock_kill() inside
rfcomm_sk_state_change() should be removed. The socket shouldn't be
killed here because only rfcomm_sock_release() calls sock_orphan(),
which it already follows up with a call to rfcomm_sock_kill().
Fixes: b7ce436a5d79 ("Bluetooth: switch to lock_sock in RFCOMM")
Link: https://syzkaller.appspot.com/bug?extid=7d51f807c81b190a127d [1]
Reported-by: syzbot+7d51f807c81b190a127d@syzkaller.appspotmail.com
Tested-by: syzbot+7d51f807c81b190a127d@syzkaller.appspotmail.com
Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Cc: Hillf Danton <hdanton@sina.com>
---
include/net/bluetooth/rfcomm.h | 3 +++
net/bluetooth/rfcomm/core.c | 2 ++
net/bluetooth/rfcomm/sock.c | 34 ++++++++++++++++++++++------------
3 files changed, 27 insertions(+), 12 deletions(-)
diff --git a/include/net/bluetooth/rfcomm.h b/include/net/bluetooth/rfcomm.h
index 99d26879b02a53..a92799fc5e74d0 100644
--- a/include/net/bluetooth/rfcomm.h
+++ b/include/net/bluetooth/rfcomm.h
@@ -171,6 +171,7 @@ struct rfcomm_dlc {
struct rfcomm_session *session;
struct sk_buff_head tx_queue;
struct timer_list timer;
+ struct work_struct state_change_work;
struct mutex lock;
unsigned long state;
@@ -186,6 +187,7 @@ struct rfcomm_dlc {
u8 sec_level;
u8 role_switch;
u32 defer_setup;
+ int err;
uint mtu;
uint cfc;
@@ -310,6 +312,7 @@ struct rfcomm_pinfo {
u8 role_switch;
};
+void __rfcomm_sk_state_change(struct work_struct *work);
int rfcomm_init_sockets(void);
void rfcomm_cleanup_sockets(void);
diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
index 7324764384b677..c6494e85cd68b2 100644
--- a/net/bluetooth/rfcomm/core.c
+++ b/net/bluetooth/rfcomm/core.c
@@ -289,6 +289,7 @@ static void rfcomm_dlc_clear_state(struct rfcomm_dlc *d)
d->flags = 0;
d->mscex = 0;
d->sec_level = BT_SECURITY_LOW;
+ d->err = 0;
d->mtu = RFCOMM_DEFAULT_MTU;
d->v24_sig = RFCOMM_V24_RTC | RFCOMM_V24_RTR | RFCOMM_V24_DV;
@@ -306,6 +307,7 @@ struct rfcomm_dlc *rfcomm_dlc_alloc(gfp_t prio)
timer_setup(&d->timer, rfcomm_dlc_timeout, 0);
skb_queue_head_init(&d->tx_queue);
+ INIT_WORK(&d->state_change_work, __rfcomm_sk_state_change);
mutex_init(&d->lock);
refcount_set(&d->refcnt, 1);
diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
index 4bf4ea6cbb5eee..4850dafbaa05fb 100644
--- a/net/bluetooth/rfcomm/sock.c
+++ b/net/bluetooth/rfcomm/sock.c
@@ -61,19 +61,22 @@ static void rfcomm_sk_data_ready(struct rfcomm_dlc *d, struct sk_buff *skb)
rfcomm_dlc_throttle(d);
}
-static void rfcomm_sk_state_change(struct rfcomm_dlc *d, int err)
+void __rfcomm_sk_state_change(struct work_struct *work)
{
+ struct rfcomm_dlc *d = container_of(work, struct rfcomm_dlc,
+ state_change_work);
struct sock *sk = d->owner, *parent;
if (!sk)
return;
- BT_DBG("dlc %p state %ld err %d", d, d->state, err);
-
lock_sock(sk);
+ rfcomm_dlc_lock(d);
- if (err)
- sk->sk_err = err;
+ BT_DBG("dlc %p state %ld err %d", d, d->state, d->err);
+
+ if (d->err)
+ sk->sk_err = d->err;
sk->sk_state = d->state;
@@ -91,15 +94,22 @@ static void rfcomm_sk_state_change(struct rfcomm_dlc *d, int err)
sk->sk_state_change(sk);
}
+ rfcomm_dlc_unlock(d);
release_sock(sk);
+ sock_put(sk);
+}
- if (parent && sock_flag(sk, SOCK_ZAPPED)) {
- /* We have to drop DLC lock here, otherwise
- * rfcomm_sock_destruct() will dead lock. */
- rfcomm_dlc_unlock(d);
- rfcomm_sock_kill(sk);
- rfcomm_dlc_lock(d);
- }
+static void rfcomm_sk_state_change(struct rfcomm_dlc *d, int err)
+{
+ struct sock *sk = d->owner;
+
+ if (!sk)
+ return;
+
+ d->err = err;
+ sock_hold(sk);
+ if (!schedule_work(&d->state_change_work))
+ sock_put(sk);
}
/* ---- Socket functions ---- */