[PATCH] freezer: Add unsafe versions of freezable_schedule_timeout_interruptible for NFS

From: zhe.he
Date: Mon Jul 06 2020 - 05:57:24 EST


From: He Zhe <zhe.he@xxxxxxxxxxxxx>

commit 0688e64bc600 ("NFS: Allow signal interruption of NFS4ERR_DELAYed operations")
introduces nfs4_delay_interruptible which also needs an _unsafe version to
avoid the following call trace for the same reason explained in
commit 416ad3c9c006 ("freezer: add unsafe versions of freezable helpers for NFS")

CPU: 4 PID: 3968 Comm: rm Tainted: G W 5.8.0-rc4 #1
Hardware name: Marvell OcteonTX CN96XX board (DT)
Call trace:
dump_backtrace+0x0/0x1dc
show_stack+0x20/0x30
dump_stack+0xdc/0x150
debug_check_no_locks_held+0x98/0xa0
nfs4_delay_interruptible+0xd8/0x120
nfs4_handle_exception+0x130/0x170
nfs4_proc_rmdir+0x8c/0x220
nfs_rmdir+0xa4/0x360
vfs_rmdir.part.0+0x6c/0x1b0
do_rmdir+0x18c/0x210
__arm64_sys_unlinkat+0x64/0x7c
el0_svc_common.constprop.0+0x7c/0x110
do_el0_svc+0x24/0xa0
el0_sync_handler+0x13c/0x1b8
el0_sync+0x158/0x180

Signed-off-by: He Zhe <zhe.he@xxxxxxxxxxxxx>
---
fs/nfs/nfs4proc.c | 2 +-
include/linux/freezer.h | 14 ++++++++++++++
2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index e32717fd1169..15ecfa474e37 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -414,7 +414,7 @@ static int nfs4_delay_interruptible(long *timeout)
{
might_sleep();

- freezable_schedule_timeout_interruptible(nfs4_update_delay(timeout));
+ freezable_schedule_timeout_interruptible_unsafe(nfs4_update_delay(timeout));
if (!signal_pending(current))
return 0;
return __fatal_signal_pending(current) ? -EINTR :-ERESTARTSYS;
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index 21f5aa0b217f..27828145ca09 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -207,6 +207,17 @@ static inline long freezable_schedule_timeout_interruptible(long timeout)
return __retval;
}

+/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
+static inline long freezable_schedule_timeout_interruptible_unsafe(long timeout)
+{
+ long __retval;
+
+ freezer_do_not_count();
+ __retval = schedule_timeout_interruptible(timeout);
+ freezer_count_unsafe();
+ return __retval;
+}
+
/* Like schedule_timeout_killable(), but should not block the freezer. */
static inline long freezable_schedule_timeout_killable(long timeout)
{
@@ -285,6 +296,9 @@ static inline void set_freezable(void) {}
#define freezable_schedule_timeout_interruptible(timeout) \
schedule_timeout_interruptible(timeout)

+#define freezable_schedule_timeout_interruptible_unsafe(timeout) \
+ schedule_timeout_interruptible(timeout)
+
#define freezable_schedule_timeout_killable(timeout) \
schedule_timeout_killable(timeout)

--
2.17.1