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Groups > linux.kernel > #1738378

[PATCH 4.9 63/77] s390/mm: fix race on mm->context.flush_mm

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.9 63/77] s390/mm: fix race on mm->context.flush_mm
Date 2017-09-24 22:50 +0200
Message-ID <utm0G-4Xd-27@gated-at.bofh.it> (permalink)
References <utlQZ-4Ti-7@gated-at.bofh.it>
Organization linux.* mail to news gateway

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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

commit 60f07c8ec5fae06c23e9fd7bab67dabce92b3414 upstream.

The order in __tlb_flush_mm_lazy is to flush TLB first and then clear
the mm->context.flush_mm bit. This can lead to missed flushes as the
bit can be set anytime, the order needs to be the other way aronud.

But this leads to a different race, __tlb_flush_mm_lazy may be called
on two CPUs concurrently. If mm->context.flush_mm is cleared first then
another CPU can bypass __tlb_flush_mm_lazy although the first CPU has
not done the flush yet. In a virtualized environment the time until the
flush is finally completed can be arbitrarily long.

Add a spinlock to serialize __tlb_flush_mm_lazy and use the function
in finish_arch_post_lock_switch as well.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/s390/include/asm/mmu.h         |    2 ++
 arch/s390/include/asm/mmu_context.h |    4 ++--
 arch/s390/include/asm/tlbflush.h    |    4 +++-
 3 files changed, 7 insertions(+), 3 deletions(-)

--- a/arch/s390/include/asm/mmu.h
+++ b/arch/s390/include/asm/mmu.h
@@ -5,6 +5,7 @@
 #include <linux/errno.h>
 
 typedef struct {
+	spinlock_t lock;
 	cpumask_t cpu_attach_mask;
 	atomic_t flush_count;
 	unsigned int flush_mm;
@@ -25,6 +26,7 @@ typedef struct {
 } mm_context_t;
 
 #define INIT_MM_CONTEXT(name)						   \
+	.context.lock =	__SPIN_LOCK_UNLOCKED(name.context.lock),	   \
 	.context.pgtable_lock =						   \
 			__SPIN_LOCK_UNLOCKED(name.context.pgtable_lock),   \
 	.context.pgtable_list = LIST_HEAD_INIT(name.context.pgtable_list), \
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -15,6 +15,7 @@
 static inline int init_new_context(struct task_struct *tsk,
 				   struct mm_struct *mm)
 {
+	spin_lock_init(&mm->context.lock);
 	spin_lock_init(&mm->context.pgtable_lock);
 	INIT_LIST_HEAD(&mm->context.pgtable_list);
 	spin_lock_init(&mm->context.gmap_lock);
@@ -111,8 +112,7 @@ static inline void finish_arch_post_lock
 		while (atomic_read(&mm->context.flush_count))
 			cpu_relax();
 		cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
-		if (mm->context.flush_mm)
-			__tlb_flush_mm(mm);
+		__tlb_flush_mm_lazy(mm);
 		preempt_enable();
 	}
 	set_fs(current->thread.mm_segment);
--- a/arch/s390/include/asm/tlbflush.h
+++ b/arch/s390/include/asm/tlbflush.h
@@ -96,10 +96,12 @@ static inline void __tlb_flush_kernel(vo
 
 static inline void __tlb_flush_mm_lazy(struct mm_struct * mm)
 {
+	spin_lock(&mm->context.lock);
 	if (mm->context.flush_mm) {
-		__tlb_flush_mm(mm);
 		mm->context.flush_mm = 0;
+		__tlb_flush_mm(mm);
 	}
+	spin_unlock(&mm->context.lock);
 }
 
 /*

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Thread

[PATCH 4.9 00/77] 4.9.52-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
  [PATCH 4.9 60/77] PCI: pciehp: Report power fault only once until we clear it Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
  [PATCH 4.9 30/77] powerpc: Fix DAR reporting when alignment handler faults Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
  [PATCH 4.9 55/77] ftrace: Fix memleak when unregistering dynamic ops when tracing disabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
  [PATCH 4.9 42/77] scsi: zfcp: trace high part of "new" 64 bit SCSI LUN Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
  [PATCH 4.9 54/77] ftrace: Fix selftest goto location on error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
  [PATCH 4.9 75/77] mac80211_hwsim: Use proper TX power Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
  [PATCH 4.9 21/77] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Fix some cases of infinite inputs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
  [PATCH 4.9 27/77] [PATCH - RESEND] crypto: AF_ALG - remove SGL terminator indicator when  chaining Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
  [PATCH 4.9 04/77] orangefs: Dont clear SGID when inheriting ACLs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
  [PATCH 4.9 06/77] drm/sun4i: Implement drm_driver lastclose to restore fbdev console Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
  [PATCH 4.9 44/77] scsi: megaraid_sas: Check valid aen class range to avoid kernel panic Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
  [PATCH 4.9 63/77] s390/mm: fix race on mm->context.flush_mm Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:50 +0200
  [PATCH 4.9 65/77] media: uvcvideo: Prevent heap overflow when accessing mapped controls Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:50 +0200
  [PATCH 4.9 67/77] bcache: initialize dirty stripes in flash_dev_run() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:50 +0200
  [PATCH 4.9 61/77] net/netfilter/nf_conntrack_core: Fix net_conntrack_lock() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:50 +0200
  [PATCH 4.9 56/77] tracing: Add barrier to trace_printk() buffer nesting modification Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 68/77] bcache: Fix leak of bdev reference Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 24/77] MIPS: math-emu: <MADDF|MSUBF>.S: Fix accuracy (32-bit case) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 74/77] mac80211: fix VLAN handling with TXQs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 59/77] PCI: shpchp: Enable bridge bus mastering if MSI is enabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 58/77] ARC: Re-enable MMU upon Machine Check exception Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 26/77] crypto: ccp - Fix XTS-AES-128 support on v5 CCPs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 66/77] PM / devfreq: Fix memory leak when fail to register device Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 64/77] media: v4l2-compat-ioctl32: Fix timespec conversion Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 69/77] bcache: do not subtract sectors_to_gc for bypassed IO Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 73/77] bcache: fix bch_hprint crash and improve output Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 62/77] s390/mm: fix local TLB flushing vs. detach of an mm address space Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 57/77] tracing: Apply trace_clock changes to instance max buffer Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 18/77] MIPS: math-emu: MINA.<D|S>: Fix some cases of infinity and zero inputs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 76/77] mac80211: flush hw_roc_start work before cancelling the ROC Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.9 39/77] scsi: zfcp: fix missing trace records for early returns in TMF eh handlers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 40/77] scsi: zfcp: fix payload with full FCP_RSP IU in SCSI trace records Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 41/77] scsi: zfcp: trace HBA FSF response by default on dismiss or timedout late response Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 34/77] skd: Submit requests to firmware before triggering the doorbell Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 33/77] skd: Avoid that module unloading triggers a use-after-free Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 50/77] scsi: sg: factor out sg_fill_request_table() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 11/77] pinctrl/amd: save pin registers over suspend/resume Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 48/77] scsi: sg: use standard lists for sg_requests Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 03/77] mm: prevent double decrease of nr_reserved_highatomic Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 35/77] scsi: zfcp: fix queuecommand for scsi_eh commands when DIX enabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 47/77] scsi: sg: remove save_scat_len Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 17/77] MIPS: math-emu: <MAXA|MINA>.<D|S>: Fix cases of both infinite inputs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 45/77] scsi: megaraid_sas: Return pended IOCTLs with cmd_status MFI_STAT_WRONG_STATE in case adapter is dead Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 31/77] block: Relax a check in blk_start_queue() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 53/77] scsi: qla2xxx: Fix an integer overflow in sysfs code Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 10/77] tty: fix __tty_insert_flip_char regression Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 29/77] ext4: fix quota inconsistency during orphan cleanup for read-only mounts Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 43/77] scsi: megaraid_sas: set minimum value of resetwaittime to be 1 secs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 12/77] Input: i8042 - add Gigabyte P57 to the keyboard reset table Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 16/77] MIPS: math-emu: <MAXA|MINA>.<D|S>: Fix cases of input values with opposite signs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 15/77] MIPS: math-emu: <MAX|MIN>.<D|S>: Fix cases of both inputs negative Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 07/77] IB/addr: Fix setting source address in addr6_resolve() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 09/77] tty: improve tty_insert_flip_char() slow path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 19/77] MIPS: math-emu: Handle zero accumulator case in MADDF and MSUBF separately Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 51/77] scsi: sg: fixup infoleak when using SG_GET_REQUEST_TABLE Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 28/77] ext4: fix incorrect quotaoff if the quota feature is enabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 05/77] IB/{qib, hfi1}: Avoid flow control testing for RDMA write operation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  [PATCH 4.9 20/77] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Fix NaN propagation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
  Re: [PATCH 4.9 00/77] 4.9.52-stable review Guenter Roeck <linux@roeck-us.net> - 2017-09-25 03:10 +0200
  Re: [PATCH 4.9 00/77] 4.9.52-stable review Tom Gall <tom.gall@linaro.org> - 2017-09-25 06:40 +0200
    Re: [PATCH 4.9 00/77] 4.9.52-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-25 08:30 +0200
  Re: [PATCH 4.9 00/77] 4.9.52-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-09-26 01:20 +0200

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