From cf124db566e6b036b8bcbe8decbed740bdfac8c6 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Mon, 8 May 2017 12:52:56 -0400 Subject: net: Fix inconsistent teardown and release of private netdev state. Network devices can allocate reasources and private memory using netdev_ops->ndo_init(). However, the release of these resources can occur in one of two different places. Either netdev_ops->ndo_uninit() or netdev->destructor(). The decision of which operation frees the resources depends upon whether it is necessary for all netdev refs to be released before it is safe to perform the freeing. netdev_ops->ndo_uninit() presumably can occur right after the NETDEV_UNREGISTER notifier completes and the unicast and multicast address lists are flushed. netdev->destructor(), on the other hand, does not run until the netdev references all go away. Further complicating the situation is that netdev->destructor() almost universally does also a free_netdev(). This creates a problem for the logic in register_netdevice(). Because all callers of register_netdevice() manage the freeing of the netdev, and invoke free_netdev(dev) if register_netdevice() fails. If netdev_ops->ndo_init() succeeds, but something else fails inside of register_netdevice(), it does call ndo_ops->ndo_uninit(). But it is not able to invoke netdev->destructor(). This is because netdev->destructor() will do a free_netdev() and then the caller of register_netdevice() will do the same. However, this means that the resources that would normally be released by netdev->destructor() will not be. Over the years drivers have added local hacks to deal with this, by invoking their destructor parts by hand when register_netdevice() fails. Many drivers do not try to deal with this, and instead we have leaks. Let's close this hole by formalizing the distinction between what private things need to be freed up by netdev->destructor() and whether the driver needs unregister_netdevice() to perform the free_netdev(). netdev->priv_destructor() performs all actions to free up the private resources that used to be freed by netdev->destructor(), except for free_netdev(). netdev->needs_free_netdev is a boolean that indicates whether free_netdev() should be done at the end of unregister_netdevice(). Now, register_netdevice() can sanely release all resources after ndo_ops->ndo_init() succeeds, by invoking both ndo_ops->ndo_uninit() and netdev->priv_destructor(). And at the end of unregister_netdevice(), we invoke netdev->priv_destructor() and optionally call free_netdev(). Signed-off-by: David S. Miller --- include/linux/netdevice.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 3f39d27decf4..ab7ca3fdc495 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1596,8 +1596,8 @@ enum netdev_priv_flags { * @rtnl_link_state: This enum represents the phases of creating * a new link * - * @destructor: Called from unregister, - * can be used to call free_netdev + * @needs_free_netdev: Should unregister perform free_netdev? + * @priv_destructor: Called from unregister * @npinfo: XXX: need comments on this one * @nd_net: Network namespace this network device is inside * @@ -1858,7 +1858,8 @@ struct net_device { RTNL_LINK_INITIALIZING, } rtnl_link_state:16; - void (*destructor)(struct net_device *dev); + bool needs_free_netdev; + void (*priv_destructor)(struct net_device *dev); #ifdef CONFIG_NETPOLL struct netpoll_info __rcu *npinfo; -- cgit v1.2.3 From 8397ed36b7c585f8d3e06c431f4137309124f78f Mon Sep 17 00:00:00 2001 From: David Ahern Date: Wed, 7 Jun 2017 12:26:23 -0600 Subject: net: ipv6: Release route when device is unregistering Roopa reported attempts to delete a bond device that is referenced in a multipath route is hanging: $ ifdown bond2 # ifupdown2 command that deletes virtual devices unregister_netdevice: waiting for bond2 to become free. Usage count = 2 Steps to reproduce: echo 1 > /proc/sys/net/ipv6/conf/all/ignore_routes_with_linkdown ip link add dev bond12 type bond ip link add dev bond13 type bond ip addr add 2001:db8:2::0/64 dev bond12 ip addr add 2001:db8:3::0/64 dev bond13 ip route add 2001:db8:33::0/64 nexthop via 2001:db8:2::2 nexthop via 2001:db8:3::2 ip link del dev bond12 ip link del dev bond13 The root cause is the recent change to keep routes on a linkdown. Update the check to detect when the device is unregistering and release the route for that case. Fixes: a1a22c12060e4 ("net: ipv6: Keep nexthop of multipath route on admin down") Reported-by: Roopa Prabhu Signed-off-by: David Ahern Acked-by: Roopa Prabhu Signed-off-by: David S. Miller --- include/linux/netdevice.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux') diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index ab7ca3fdc495..846193dfb0ac 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -4262,6 +4262,11 @@ static inline const char *netdev_name(const struct net_device *dev) return dev->name; } +static inline bool netdev_unregistering(const struct net_device *dev) +{ + return dev->reg_state == NETREG_UNREGISTERING; +} + static inline const char *netdev_reg_state(const struct net_device *dev) { switch (dev->reg_state) { -- cgit v1.2.3 From 19e72d3abb63cb16d021a4066ce1a18880509e99 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Thu, 9 Feb 2017 17:28:50 -0800 Subject: configfs: Introduce config_item_get_unless_zero() Signed-off-by: Bart Van Assche [hch: minor style tweak] Signed-off-by: Christoph Hellwig --- include/linux/configfs.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/configfs.h b/include/linux/configfs.h index 2319b8c108e8..c96709049683 100644 --- a/include/linux/configfs.h +++ b/include/linux/configfs.h @@ -74,7 +74,8 @@ extern void config_item_init_type_name(struct config_item *item, const char *name, struct config_item_type *type); -extern struct config_item * config_item_get(struct config_item *); +extern struct config_item *config_item_get(struct config_item *); +extern struct config_item *config_item_get_unless_zero(struct config_item *); extern void config_item_put(struct config_item *); struct config_item_type { -- cgit v1.2.3 From db46a0e1be7eac45d0bb1bdcd438b8d47c920451 Mon Sep 17 00:00:00 2001 From: Magnus Damm Date: Wed, 14 Jun 2017 16:15:24 +0900 Subject: net: update undefined ->ndo_change_mtu() comment Update ->ndo_change_mtu() callback comment to remove text about returning error in case of undefined callback. This change makes the comment match the existing code behavior. Signed-off-by: Magnus Damm Signed-off-by: David S. Miller --- include/linux/netdevice.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 846193dfb0ac..4ed952c17fc7 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -914,8 +914,7 @@ struct xfrmdev_ops { * * int (*ndo_change_mtu)(struct net_device *dev, int new_mtu); * Called when a user wants to change the Maximum Transfer Unit - * of a device. If not defined, any request to change MTU will - * will return an error. + * of a device. * * void (*ndo_tx_timeout)(struct net_device *dev); * Callback used when the transmitter has not made any progress -- cgit v1.2.3 From dc9edc44de6cd7cc8cc7f5b36c1adb221eda3207 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Wed, 14 Jun 2017 13:27:50 -0600 Subject: block: Fix a blk_exit_rl() regression Avoid that the following complaint is reported: BUG: sleeping function called from invalid context at kernel/workqueue.c:2790 in_atomic(): 1, irqs_disabled(): 0, pid: 41, name: rcuop/3 1 lock held by rcuop/3/41: #0: (rcu_callback){......}, at: [] rcu_nocb_kthread+0x282/0x500 Call Trace: dump_stack+0x86/0xcf ___might_sleep+0x174/0x260 __might_sleep+0x4a/0x80 flush_work+0x7e/0x2e0 __cancel_work_timer+0x143/0x1c0 cancel_work_sync+0x10/0x20 blk_throtl_exit+0x25/0x60 blkcg_exit_queue+0x35/0x40 blk_release_queue+0x42/0x130 kobject_put+0xa9/0x190 This happens since we invoke callbacks that need to block from the queue release handler. Fix this by pushing the final release to a workqueue. Reported-by: Ross Zwisler Fixes: commit b425e5049258 ("block: Avoid that blk_exit_rl() triggers a use-after-free") Signed-off-by: Bart Van Assche Tested-by: Ross Zwisler Updated changelog Signed-off-by: Jens Axboe --- include/linux/blkdev.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index ab92c4ea138b..b74a3edcb3da 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -586,6 +586,8 @@ struct request_queue { size_t cmd_size; void *rq_alloc_data; + + struct work_struct release_work; }; #define QUEUE_FLAG_QUEUED 1 /* uses generic tag queueing */ -- cgit v1.2.3 From c926820085437a27b27e78996b2c7a5ad94e8055 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 15 Jun 2017 13:46:00 +0200 Subject: firmware: dmi_scan: Make dmi_walk and dmi_walk_early return real error codes Currently they return -1 on error, which will confuse callers if they try to interpret it as a normal negative error code. Signed-off-by: Andy Lutomirski Signed-off-by: Darren Hart (VMware) Signed-off-by: Jean Delvare --- include/linux/dmi.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/dmi.h b/include/linux/dmi.h index 5e9c74cf8894..9bbf21a516e4 100644 --- a/include/linux/dmi.h +++ b/include/linux/dmi.h @@ -136,7 +136,7 @@ static inline int dmi_name_in_vendors(const char *s) { return 0; } static inline int dmi_name_in_serial(const char *s) { return 0; } #define dmi_available 0 static inline int dmi_walk(void (*decode)(const struct dmi_header *, void *), - void *private_data) { return -1; } + void *private_data) { return -ENXIO; } static inline bool dmi_match(enum dmi_field f, const char *str) { return false; } static inline void dmi_memdev_name(u16 handle, const char **bank, -- cgit v1.2.3 From 1be7107fbe18eed3e319a6c3e83c78254b693acb Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 19 Jun 2017 04:03:24 -0700 Subject: mm: larger stack guard gap, between vmas Stack guard page is a useful feature to reduce a risk of stack smashing into a different mapping. We have been using a single page gap which is sufficient to prevent having stack adjacent to a different mapping. But this seems to be insufficient in the light of the stack usage in userspace. E.g. glibc uses as large as 64kB alloca() in many commonly used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX] which is 256kB or stack strings with MAX_ARG_STRLEN. This will become especially dangerous for suid binaries and the default no limit for the stack size limit because those applications can be tricked to consume a large portion of the stack and a single glibc call could jump over the guard page. These attacks are not theoretical, unfortunatelly. Make those attacks less probable by increasing the stack guard gap to 1MB (on systems with 4k pages; but make it depend on the page size because systems with larger base pages might cap stack allocations in the PAGE_SIZE units) which should cover larger alloca() and VLA stack allocations. It is obviously not a full fix because the problem is somehow inherent, but it should reduce attack space a lot. One could argue that the gap size should be configurable from userspace, but that can be done later when somebody finds that the new 1MB is wrong for some special case applications. For now, add a kernel command line option (stack_guard_gap) to specify the stack gap size (in page units). Implementation wise, first delete all the old code for stack guard page: because although we could get away with accounting one extra page in a stack vma, accounting a larger gap can break userspace - case in point, a program run with "ulimit -S -v 20000" failed when the 1MB gap was counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK and strict non-overcommit mode. Instead of keeping gap inside the stack vma, maintain the stack guard gap as a gap between vmas: using vm_start_gap() in place of vm_start (or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few places which need to respect the gap - mainly arch_get_unmapped_area(), and and the vma tree's subtree_gap support for that. Original-patch-by: Oleg Nesterov Original-patch-by: Michal Hocko Signed-off-by: Hugh Dickins Acked-by: Michal Hocko Tested-by: Helge Deller # parisc Signed-off-by: Linus Torvalds --- include/linux/mm.h | 53 +++++++++++++++++++++++++---------------------------- 1 file changed, 25 insertions(+), 28 deletions(-) (limited to 'include/linux') diff --git a/include/linux/mm.h b/include/linux/mm.h index b892e95d4929..6f543a47fc92 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1393,12 +1393,6 @@ int clear_page_dirty_for_io(struct page *page); int get_cmdline(struct task_struct *task, char *buffer, int buflen); -/* Is the vma a continuation of the stack vma above it? */ -static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr) -{ - return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN); -} - static inline bool vma_is_anonymous(struct vm_area_struct *vma) { return !vma->vm_ops; @@ -1414,28 +1408,6 @@ bool vma_is_shmem(struct vm_area_struct *vma); static inline bool vma_is_shmem(struct vm_area_struct *vma) { return false; } #endif -static inline int stack_guard_page_start(struct vm_area_struct *vma, - unsigned long addr) -{ - return (vma->vm_flags & VM_GROWSDOWN) && - (vma->vm_start == addr) && - !vma_growsdown(vma->vm_prev, addr); -} - -/* Is the vma a continuation of the stack vma below it? */ -static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr) -{ - return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP); -} - -static inline int stack_guard_page_end(struct vm_area_struct *vma, - unsigned long addr) -{ - return (vma->vm_flags & VM_GROWSUP) && - (vma->vm_end == addr) && - !vma_growsup(vma->vm_next, addr); -} - int vma_is_stack_for_current(struct vm_area_struct *vma); extern unsigned long move_page_tables(struct vm_area_struct *vma, @@ -2222,6 +2194,7 @@ void page_cache_async_readahead(struct address_space *mapping, pgoff_t offset, unsigned long size); +extern unsigned long stack_guard_gap; /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */ extern int expand_stack(struct vm_area_struct *vma, unsigned long address); @@ -2250,6 +2223,30 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m return vma; } +static inline unsigned long vm_start_gap(struct vm_area_struct *vma) +{ + unsigned long vm_start = vma->vm_start; + + if (vma->vm_flags & VM_GROWSDOWN) { + vm_start -= stack_guard_gap; + if (vm_start > vma->vm_start) + vm_start = 0; + } + return vm_start; +} + +static inline unsigned long vm_end_gap(struct vm_area_struct *vma) +{ + unsigned long vm_end = vma->vm_end; + + if (vma->vm_flags & VM_GROWSUP) { + vm_end += stack_guard_gap; + if (vm_end < vma->vm_end) + vm_end = -PAGE_SIZE; + } + return vm_end; +} + static inline unsigned long vma_pages(struct vm_area_struct *vma) { return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; -- cgit v1.2.3 From ceea5e3771ed2378668455fa21861bead7504df5 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Thu, 8 Jun 2017 16:44:20 -0700 Subject: time: Fix clock->read(clock) race around clocksource changes In tests, which excercise switching of clocksources, a NULL pointer dereference can be observed on AMR64 platforms in the clocksource read() function: u64 clocksource_mmio_readl_down(struct clocksource *c) { return ~(u64)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask; } This is called from the core timekeeping code via: cycle_now = tkr->read(tkr->clock); tkr->read is the cached tkr->clock->read() function pointer. When the clocksource is changed then tkr->clock and tkr->read are updated sequentially. The code above results in a sequential load operation of tkr->read and tkr->clock as well. If the store to tkr->clock hits between the loads of tkr->read and tkr->clock, then the old read() function is called with the new clock pointer. As a consequence the read() function dereferences a different data structure and the resulting 'reg' pointer can point anywhere including NULL. This problem was introduced when the timekeeping code was switched over to use struct tk_read_base. Before that, it was theoretically possible as well when the compiler decided to reload clock in the code sequence: now = tk->clock->read(tk->clock); Add a helper function which avoids the issue by reading tk_read_base->clock once into a local variable clk and then issue the read function via clk->read(clk). This guarantees that the read() function always gets the proper clocksource pointer handed in. Since there is now no use for the tkr.read pointer, this patch also removes it, and to address stopping the fast timekeeper during suspend/resume, it introduces a dummy clocksource to use rather then just a dummy read function. Signed-off-by: John Stultz Acked-by: Ingo Molnar Cc: Prarit Bhargava Cc: Richard Cochran Cc: Stephen Boyd Cc: stable Cc: Miroslav Lichvar Cc: Daniel Mentz Link: http://lkml.kernel.org/r/1496965462-20003-2-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner --- include/linux/timekeeper_internal.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h index 110f4532188c..e9834ada4d0c 100644 --- a/include/linux/timekeeper_internal.h +++ b/include/linux/timekeeper_internal.h @@ -29,7 +29,6 @@ */ struct tk_read_base { struct clocksource *clock; - u64 (*read)(struct clocksource *cs); u64 mask; u64 cycle_last; u32 mult; -- cgit v1.2.3 From 3d88d56c5873f6eebe23e05c3da701960146b801 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Thu, 8 Jun 2017 16:44:21 -0700 Subject: time: Fix CLOCK_MONOTONIC_RAW sub-nanosecond accounting Due to how the MONOTONIC_RAW accumulation logic was handled, there is the potential for a 1ns discontinuity when we do accumulations. This small discontinuity has for the most part gone un-noticed, but since ARM64 enabled CLOCK_MONOTONIC_RAW in their vDSO clock_gettime implementation, we've seen failures with the inconsistency-check test in kselftest. This patch addresses the issue by using the same sub-ns accumulation handling that CLOCK_MONOTONIC uses, which avoids the issue for in-kernel users. Since the ARM64 vDSO implementation has its own clock_gettime calculation logic, this patch reduces the frequency of errors, but failures are still seen. The ARM64 vDSO will need to be updated to include the sub-nanosecond xtime_nsec values in its calculation for this issue to be completely fixed. Signed-off-by: John Stultz Tested-by: Daniel Mentz Cc: Prarit Bhargava Cc: Kevin Brodsky Cc: Richard Cochran Cc: Stephen Boyd Cc: Will Deacon Cc: "stable #4 . 8+" Cc: Miroslav Lichvar Link: http://lkml.kernel.org/r/1496965462-20003-3-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner --- include/linux/timekeeper_internal.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h index e9834ada4d0c..f7043ccca81c 100644 --- a/include/linux/timekeeper_internal.h +++ b/include/linux/timekeeper_internal.h @@ -57,7 +57,7 @@ struct tk_read_base { * interval. * @xtime_remainder: Shifted nano seconds left over when rounding * @cycle_interval - * @raw_interval: Raw nano seconds accumulated per NTP interval. + * @raw_interval: Shifted raw nano seconds accumulated per NTP interval. * @ntp_error: Difference between accumulated time and NTP time in ntp * shifted nano seconds. * @ntp_error_shift: Shift conversion between clock shifted nano seconds and @@ -99,7 +99,7 @@ struct timekeeper { u64 cycle_interval; u64 xtime_interval; s64 xtime_remainder; - u32 raw_interval; + u64 raw_interval; /* The ntp_tick_length() value currently being used. * This cached copy ensures we consistently apply the tick * length for an entire tick, as ntp_tick_length may change -- cgit v1.2.3 From 8e8320c9315c47a6a090188720ccff32a6a6ba18 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 20 Jun 2017 17:56:13 -0600 Subject: blk-mq: fix performance regression with shared tags If we have shared tags enabled, then every IO completion will trigger a full loop of every queue belonging to a tag set, and every hardware queue for each of those queues, even if nothing needs to be done. This causes a massive performance regression if you have a lot of shared devices. Instead of doing this huge full scan on every IO, add an atomic counter to the main queue that tracks how many hardware queues have been marked as needing a restart. With that, we can avoid looking for restartable queues, if we don't have to. Max reports that this restores performance. Before this patch, 4K IOPS was limited to 22-23K IOPS. With the patch, we are running at 950-970K IOPS. Fixes: 6d8c6c0f97ad ("blk-mq: Restart a single queue if tag sets are shared") Reported-by: Max Gurtovoy Tested-by: Max Gurtovoy Reviewed-by: Bart Van Assche Tested-by: Bart Van Assche Signed-off-by: Jens Axboe --- include/linux/blkdev.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index b74a3edcb3da..1ddd36bd2173 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -391,6 +391,8 @@ struct request_queue { int nr_rqs[2]; /* # allocated [a]sync rqs */ int nr_rqs_elvpriv; /* # allocated rqs w/ elvpriv */ + atomic_t shared_hctx_restart; + struct blk_queue_stats *stats; struct rq_wb *rq_wb; -- cgit v1.2.3 From 3b7b314053d021601940c50b07f5f1423ae67e21 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 23 Jun 2017 15:08:52 -0700 Subject: slub: make sysfs file removal asynchronous Commit bf5eb3de3847 ("slub: separate out sysfs_slab_release() from sysfs_slab_remove()") made slub sysfs file removals synchronous to kmem_cache shutdown. Unfortunately, this created a possible ABBA deadlock between slab_mutex and sysfs draining mechanism triggering the following lockdep warning. ====================================================== [ INFO: possible circular locking dependency detected ] 4.10.0-test+ #48 Not tainted ------------------------------------------------------- rmmod/1211 is trying to acquire lock: (s_active#120){++++.+}, at: [] kernfs_remove+0x23/0x40 but task is already holding lock: (slab_mutex){+.+.+.}, at: [] kmem_cache_destroy+0x41/0x2d0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (slab_mutex){+.+.+.}: lock_acquire+0xf6/0x1f0 __mutex_lock+0x75/0x950 mutex_lock_nested+0x1b/0x20 slab_attr_store+0x75/0xd0 sysfs_kf_write+0x45/0x60 kernfs_fop_write+0x13c/0x1c0 __vfs_write+0x28/0x120 vfs_write+0xc8/0x1e0 SyS_write+0x49/0xa0 entry_SYSCALL_64_fastpath+0x1f/0xc2 -> #0 (s_active#120){++++.+}: __lock_acquire+0x10ed/0x1260 lock_acquire+0xf6/0x1f0 __kernfs_remove+0x254/0x320 kernfs_remove+0x23/0x40 sysfs_remove_dir+0x51/0x80 kobject_del+0x18/0x50 __kmem_cache_shutdown+0x3e6/0x460 kmem_cache_destroy+0x1fb/0x2d0 kvm_exit+0x2d/0x80 [kvm] vmx_exit+0x19/0xa1b [kvm_intel] SyS_delete_module+0x198/0x1f0 entry_SYSCALL_64_fastpath+0x1f/0xc2 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(slab_mutex); lock(s_active#120); lock(slab_mutex); lock(s_active#120); *** DEADLOCK *** 2 locks held by rmmod/1211: #0: (cpu_hotplug.dep_map){++++++}, at: [] get_online_cpus+0x37/0x80 #1: (slab_mutex){+.+.+.}, at: [] kmem_cache_destroy+0x41/0x2d0 stack backtrace: CPU: 3 PID: 1211 Comm: rmmod Not tainted 4.10.0-test+ #48 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012 Call Trace: print_circular_bug+0x1be/0x210 __lock_acquire+0x10ed/0x1260 lock_acquire+0xf6/0x1f0 __kernfs_remove+0x254/0x320 kernfs_remove+0x23/0x40 sysfs_remove_dir+0x51/0x80 kobject_del+0x18/0x50 __kmem_cache_shutdown+0x3e6/0x460 kmem_cache_destroy+0x1fb/0x2d0 kvm_exit+0x2d/0x80 [kvm] vmx_exit+0x19/0xa1b [kvm_intel] SyS_delete_module+0x198/0x1f0 ? SyS_delete_module+0x5/0x1f0 entry_SYSCALL_64_fastpath+0x1f/0xc2 It'd be the cleanest to deal with the issue by removing sysfs files without holding slab_mutex before the rest of shutdown; however, given the current code structure, it is pretty difficult to do so. This patch punts sysfs file removal to a work item. Before commit bf5eb3de3847, the removal was punted to a RCU delayed work item which is executed after release. Now, we're punting to a different work item on shutdown which still maintains the goal removing the sysfs files earlier when destroying kmem_caches. Link: http://lkml.kernel.org/r/20170620204512.GI21326@htj.duckdns.org Fixes: bf5eb3de3847 ("slub: separate out sysfs_slab_release() from sysfs_slab_remove()") Signed-off-by: Tejun Heo Reported-by: Steven Rostedt (VMware) Tested-by: Steven Rostedt (VMware) Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/slub_def.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index 07ef550c6627..93315d6b21a8 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -84,6 +84,7 @@ struct kmem_cache { int red_left_pad; /* Left redzone padding size */ #ifdef CONFIG_SYSFS struct kobject kobj; /* For sysfs */ + struct work_struct kobj_remove_work; #endif #ifdef CONFIG_MEMCG struct memcg_cache_params memcg_params; -- cgit v1.2.3