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| author |   Dan Williams <dan.j.williams@intel.com> | 2017-04-07 16:42:08 -0700 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2017-04-12 13:45:18 -0700 |
| commit | 956a4cd2c957acf638ff29951aabaa9d8e92bbc2 (patch) | |
| tree | d4e8def7593d04b58bad676f1329cdd8446bd00f /drivers/dax/Kconfig | |
| parent | libnvdimm: band aid btt vs clear poison locking (diff) | |
| download | linux-dev-956a4cd2c957acf638ff29951aabaa9d8e92bbc2.tar.xz linux-dev-956a4cd2c957acf638ff29951aabaa9d8e92bbc2.zip | |
device-dax: switch to srcu, fix rcu_read_lock() vs pte allocation
The following warning triggers with a new unit test that stresses the
device-dax interface.
===============================
[ ERR: suspicious RCU usage. ]
4.11.0-rc4+ #1049 Tainted: G O
-------------------------------
./include/linux/rcupdate.h:521 Illegal context switch in RCU read-side critical section!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 0
2 locks held by fio/9070:
#0: (&mm->mmap_sem){++++++}, at: [<ffffffff8d0739d7>] __do_page_fault+0x167/0x4f0
#1: (rcu_read_lock){......}, at: [<ffffffffc03fbd02>] dax_dev_huge_fault+0x32/0x620 [dax]
Call Trace:
dump_stack+0x86/0xc3
lockdep_rcu_suspicious+0xd7/0x110
___might_sleep+0xac/0x250
__might_sleep+0x4a/0x80
__alloc_pages_nodemask+0x23a/0x360
alloc_pages_current+0xa1/0x1f0
pte_alloc_one+0x17/0x80
__pte_alloc+0x1e/0x120
__get_locked_pte+0x1bf/0x1d0
insert_pfn.isra.70+0x3a/0x100
? lookup_memtype+0xa6/0xd0
vm_insert_mixed+0x64/0x90
dax_dev_huge_fault+0x520/0x620 [dax]
? dax_dev_huge_fault+0x32/0x620 [dax]
dax_dev_fault+0x10/0x20 [dax]
__do_fault+0x1e/0x140
__handle_mm_fault+0x9af/0x10d0
handle_mm_fault+0x16d/0x370
? handle_mm_fault+0x47/0x370
__do_page_fault+0x28c/0x4f0
trace_do_page_fault+0x58/0x2a0
do_async_page_fault+0x1a/0xa0
async_page_fault+0x28/0x30
Inserting a page table entry may trigger an allocation while we are
holding a read lock to keep the device instance alive for the duration
of the fault. Use srcu for this keep-alive protection.
Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap")
Cc: <stable@vger.kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/dax/Kconfig')
| -rw-r--r-- | drivers/dax/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig index 3e2ab3b14eea..9e95bf94eb13 100644 --- a/drivers/dax/Kconfig +++ b/drivers/dax/Kconfig @@ -2,6 +2,7 @@ menuconfig DEV_DAX tristate "DAX: direct access to differentiated memory" default m if NVDIMM_DAX depends on TRANSPARENT_HUGEPAGE + select SRCU help Support raw access to differentiated (persistence, bandwidth, latency...) memory via an mmap(2) capable character |