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Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0278-mm-zswap-Do-not-disable-preemption-in-zswap_frontswa.patch | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/debian/patches-rt/0278-mm-zswap-Do-not-disable-preemption-in-zswap_frontswa.patch b/debian/patches-rt/0278-mm-zswap-Do-not-disable-preemption-in-zswap_frontswa.patch new file mode 100644 index 000000000..b44e7ef6e --- /dev/null +++ b/debian/patches-rt/0278-mm-zswap-Do-not-disable-preemption-in-zswap_frontswa.patch @@ -0,0 +1,127 @@ +From f41d5cdc361ba012b59e23b78fe3501b16cfda3d Mon Sep 17 00:00:00 2001 +From: "Luis Claudio R. Goncalves" <lclaudio@uudg.org> +Date: Tue, 25 Jun 2019 11:28:04 -0300 +Subject: [PATCH 278/347] mm/zswap: Do not disable preemption in + zswap_frontswap_store() +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz + +[ 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); +-- +2.36.1 + |