Merging debian version 4.19.260-1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 123 insertions, 0 deletions

diff --git a/debian/patches-rt/0277-mm-zswap-Do-not-disable-preemption-in-zswap_frontswa.patch b/debian/patches-rt/0277-mm-zswap-Do-not-disable-preemption-in-zswap_frontswa.patch
new file mode 100644
index 000000000..e85c24bc9
--- /dev/null
+++ b/debian/patches-rt/0277-mm-zswap-Do-not-disable-preemption-in-zswap_frontswa.patch
@@ -0,0 +1,123 @@
+From: "Luis Claudio R. Goncalves" <lclaudio@uudg.org>
+Date: Tue, 25 Jun 2019 11:28:04 -0300
+Subject: [PATCH 277/342] mm/zswap: Do not disable preemption in
+ zswap_frontswap_store()
+Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=bf2f37b64408cdd6fd6be0309d0a7bfe88a20d29
+
+[ Upstream commit 4e4cf4be79635e67144632d9135286381acbc95a ]
+
+Zswap causes "BUG: scheduling while atomic" by blocking on a rt_spin_lock() with
+preemption disabled. The preemption is disabled by get_cpu_var() in
+zswap_frontswap_store() to protect the access of the zswap_dstmem percpu variable.
+
+Use get_locked_var() to protect the percpu zswap_dstmem variable, making the
+code preemptive.
+
+As get_cpu_ptr() also disables preemption, replace it by this_cpu_ptr() and
+remove the counterpart put_cpu_ptr().
+
+Steps to Reproduce:
+
+    1. # grubby --args "zswap.enabled=1" --update-kernel DEFAULT
+    2. # reboot
+    3. Calculate the amount o memory to be used by the test:
+       ---> grep MemAvailable /proc/meminfo
+       ---> Add 25% ~ 50% to that value
+    4. # stress --vm 1 --vm-bytes ${MemAvailable+25%} --timeout 240s
+
+Usually, in less than 5 minutes the backtrace listed below appears, followed
+by a kernel panic:
+
+| BUG: scheduling while atomic: kswapd1/181/0x00000002
+|
+| Preemption disabled at:
+| [<ffffffff8b2a6cda>] zswap_frontswap_store+0x21a/0x6e1
+|
+| Kernel panic - not syncing: scheduling while atomic
+| CPU: 14 PID: 181 Comm: kswapd1 Kdump: loaded Not tainted 5.0.14-rt9 #1
+| Hardware name: AMD Pence/Pence, BIOS WPN2321X_Weekly_12_03_21 03/19/2012
+| Call Trace:
+|  panic+0x106/0x2a7
+|  __schedule_bug.cold+0x3f/0x51
+|  __schedule+0x5cb/0x6f0
+|  schedule+0x43/0xd0
+|  rt_spin_lock_slowlock_locked+0x114/0x2b0
+|  rt_spin_lock_slowlock+0x51/0x80
+|  zbud_alloc+0x1da/0x2d0
+|  zswap_frontswap_store+0x31a/0x6e1
+|  __frontswap_store+0xab/0x130
+|  swap_writepage+0x39/0x70
+|  pageout.isra.0+0xe3/0x320
+|  shrink_page_list+0xa8e/0xd10
+|  shrink_inactive_list+0x251/0x840
+|  shrink_node_memcg+0x213/0x770
+|  shrink_node+0xd9/0x450
+|  balance_pgdat+0x2d5/0x510
+|  kswapd+0x218/0x470
+|  kthread+0xfb/0x130
+|  ret_from_fork+0x27/0x50
+
+Cc: stable-rt@vger.kernel.org
+Reported-by: Ping Fang <pifang@redhat.com>
+Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
+Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
+---
+ mm/zswap.c | 12 +++++++-----
+ 1 file changed, 7 insertions(+), 5 deletions(-)
+
+diff --git a/mm/zswap.c b/mm/zswap.c
+index cd91fd9d96b8..420225d3ff0b 100644
+--- a/mm/zswap.c
++++ b/mm/zswap.c
+@@ -27,6 +27,7 @@
+ #include <linux/highmem.h>
+ #include <linux/slab.h>
+ #include <linux/spinlock.h>
++#include <linux/locallock.h>
+ #include <linux/types.h>
+ #include <linux/atomic.h>
+ #include <linux/frontswap.h>
+@@ -990,6 +991,8 @@ static void zswap_fill_page(void *ptr, unsigned long value)
+ 	memset_l(page, value, PAGE_SIZE / sizeof(unsigned long));
+ }
+ 
++/* protect zswap_dstmem from concurrency */
++static DEFINE_LOCAL_IRQ_LOCK(zswap_dstmem_lock);
+ /*********************************
+ * frontswap hooks
+ **********************************/
+@@ -1066,12 +1069,11 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
+ 	}
+ 
+ 	/* compress */
+-	dst = get_cpu_var(zswap_dstmem);
+-	tfm = *get_cpu_ptr(entry->pool->tfm);
++	dst = get_locked_var(zswap_dstmem_lock, zswap_dstmem);
++	tfm = *this_cpu_ptr(entry->pool->tfm);
+ 	src = kmap_atomic(page);
+ 	ret = crypto_comp_compress(tfm, src, PAGE_SIZE, dst, &dlen);
+ 	kunmap_atomic(src);
+-	put_cpu_ptr(entry->pool->tfm);
+ 	if (ret) {
+ 		ret = -EINVAL;
+ 		goto put_dstmem;
+@@ -1094,7 +1096,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
+ 	memcpy(buf, &zhdr, hlen);
+ 	memcpy(buf + hlen, dst, dlen);
+ 	zpool_unmap_handle(entry->pool->zpool, handle);
+-	put_cpu_var(zswap_dstmem);
++	put_locked_var(zswap_dstmem_lock, zswap_dstmem);
+ 
+ 	/* populate entry */
+ 	entry->offset = offset;
+@@ -1122,7 +1124,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
+ 	return 0;
+ 
+ put_dstmem:
+-	put_cpu_var(zswap_dstmem);
++	put_locked_var(zswap_dstmem_lock, zswap_dstmem);
+ 	zswap_pool_put(entry->pool);
+ freepage:
+ 	zswap_entry_cache_free(entry);