kernel/linux.git/lib, branch v4.14.78

scsi: klist: Make it safe to use klists in atomic context

2018-10-04T00:00:48+00:00

[ Upstream commit 624fa7790f80575a4ec28fbdb2034097dc18d051 ] In the scsi_transport_srp implementation it cannot be avoided to iterate over a klist from atomic context when using the legacy block layer instead of blk-mq. Hence this patch that makes it safe to use klists in atomic context. This patch avoids that lockdep reports the following: WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&(&k->k_lock)->rlock); local_irq_disable(); lock(&(&q->__queue_lock)->rlock); lock(&(&k->k_lock)->rlock); lock(&(&q->__queue_lock)->rlock); stack backtrace: Workqueue: kblockd blk_timeout_work Call Trace: dump_stack+0xa4/0xf5 check_usage+0x6e6/0x700 __lock_acquire+0x185d/0x1b50 lock_acquire+0xd2/0x260 _raw_spin_lock+0x32/0x50 klist_next+0x47/0x190 device_for_each_child+0x8e/0x100 srp_timed_out+0xaf/0x1d0 [scsi_transport_srp] scsi_times_out+0xd4/0x410 [scsi_mod] blk_rq_timed_out+0x36/0x70 blk_timeout_work+0x1b5/0x220 process_one_work+0x4fe/0xad0 worker_thread+0x63/0x5a0 kthread+0x1c1/0x1e0 ret_from_fork+0x24/0x30 See also commit c9ddf73476ff ("scsi: scsi_transport_srp: Fix shost to rport translation"). Signed-off-by: Bart Van Assche Cc: Martin K. Petersen Cc: James Bottomley Acked-by: Greg Kroah-Hartman Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

rhashtable: add schedule points

2018-09-19T20:43:45+00:00

Rehashing and destroying large hash table takes a lot of time, and happens in process context. It is safe to add cond_resched() in rhashtable_rehash_table() and rhashtable_free_and_destroy() Signed-off-by: Eric Dumazet Acked-by: Herbert Xu Signed-off-by: David S. Miller (cherry picked from commit ae6da1f503abb5a5081f9f6c4a6881de97830f3e) Signed-off-by: Greg Kroah-Hartman

debugobjects: Make stack check warning more informative

2018-09-15T07:45:35+00:00

commit fc91a3c4c27acdca0bc13af6fbb68c35cfd519f2 upstream. While debugging an issue debugobject tracking warned about an annotation issue of an object on stack. It turned out that the issue was due to the object in concern being on a different stack which was due to another issue. Thomas suggested to print the pointers and the location of the stack for the currently running task. This helped to figure out that the object was on the wrong stack. As this is general useful information for debugging similar issues, make the error message more informative by printing the pointers. [ tglx: Massaged changelog ] Signed-off-by: Joel Fernandes (Google) Signed-off-by: Thomas Gleixner Acked-by: Waiman Long Acked-by: Yang Shi Cc: kernel-team@android.com Cc: Arnd Bergmann Cc: astrachan@google.com Link: https://lkml.kernel.org/r/20180723212531.202328-1-joel@joelfernandes.org Signed-off-by: Greg Kroah-Hartman

printk/nmi: Prevent deadlock when accessing the main log buffer in NMI

2018-09-05T07:26:35+00:00

commit 03fc7f9c99c1e7ae2925d459e8487f1a6f199f79 upstream. The commit 719f6a7040f1bdaf96 ("printk: Use the main logbuf in NMI when logbuf_lock is available") brought back the possible deadlocks in printk() and NMI. The check of logbuf_lock is done only in printk_nmi_enter() to prevent mixed output. But another CPU might take the lock later, enter NMI, and: + Both NMIs might be serialized by yet another lock, for example, the one in nmi_cpu_backtrace(). + The other CPU might get stopped in NMI, see smp_send_stop() in panic(). The only safe solution is to use trylock when storing the message into the main log-buffer. It might cause reordering when some lines go to the main lock buffer directly and others are delayed via the per-CPU buffer. It means that it is not useful in general. This patch replaces the problematic NMI deferred context with NMI direct context. It can be used to mark a code that might produce many messages in NMI and the risk of losing them is more critical than problems with eventual reordering. The context is then used when dumping trace buffers on oops. It was the primary motivation for the original fix. Also the reordering is even smaller issue there because some traces have their own time stamps. Finally, nmi_cpu_backtrace() need not longer be serialized because it will always us the per-CPU buffers again. Fixes: 719f6a7040f1bdaf96 ("printk: Use the main logbuf in NMI when logbuf_lock is available") Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20180627142028.11259-1-pmladek@suse.com To: Steven Rostedt Cc: Peter Zijlstra Cc: Tetsuo Handa Cc: Sergey Senozhatsky Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org Acked-by: Sergey Senozhatsky Signed-off-by: Petr Mladek Signed-off-by: Greg Kroah-Hartman

ioremap: Update pgtable free interfaces with addr

2018-08-17T19:01:11+00:00

commit 785a19f9d1dd8a4ab2d0633be4656653bd3de1fc upstream. The following kernel panic was observed on ARM64 platform due to a stale TLB entry. 1. ioremap with 4K size, a valid pte page table is set. 2. iounmap it, its pte entry is set to 0. 3. ioremap the same address with 2M size, update its pmd entry with a new value. 4. CPU may hit an exception because the old pmd entry is still in TLB, which leads to a kernel panic. Commit b6bdb7517c3d ("mm/vmalloc: add interfaces to free unmapped page table") has addressed this panic by falling to pte mappings in the above case on ARM64. To support pmd mappings in all cases, TLB purge needs to be performed in this case on ARM64. Add a new arg, 'addr', to pud_free_pmd_page() and pmd_free_pte_page() so that TLB purge can be added later in seprate patches. [toshi.kani@hpe.com: merge changes, rewrite patch description] Fixes: 28ee90fe6048 ("x86/mm: implement free pmd/pte page interfaces") Signed-off-by: Chintan Pandya Signed-off-by: Toshi Kani Signed-off-by: Thomas Gleixner Cc: mhocko@suse.com Cc: akpm@linux-foundation.org Cc: hpa@zytor.com Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: Will Deacon Cc: Joerg Roedel Cc: stable@vger.kernel.org Cc: Andrew Morton Cc: Michal Hocko Cc: "H. Peter Anvin" Cc: Link: https://lkml.kernel.org/r/20180627141348.21777-3-toshi.kani@hpe.com Signed-off-by: Greg Kroah-Hartman

lib/rhashtable: consider param->min_size when setting initial table size

2018-07-25T09:25:09+00:00

[ Upstream commit 107d01f5ba10f4162c38109496607eb197059064 ] rhashtable_init() currently does not take into account the user-passed min_size parameter unless param->nelem_hint is set as well. As such, the default size (number of buckets) will always be HASH_DEFAULT_SIZE even if the smallest allowed size is larger than that. Remediate this by unconditionally calling into rounded_hashtable_size() and handling things accordingly. Signed-off-by: Davidlohr Bueso Acked-by: Herbert Xu Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

lib/vsprintf: Remove atomic-unsafe support for %pCr

2018-07-03T09:24:48+00:00

commit 666902e42fd8344b923c02dc5b0f37948ff4f225 upstream. "%pCr" formats the current rate of a clock, and calls clk_get_rate(). The latter obtains a mutex, hence it must not be called from atomic context. Remove support for this rarely-used format, as vsprintf() (and e.g. printk()) must be callable from any context. Any remaining out-of-tree users will start seeing the clock's name printed instead of its rate. Reported-by: Jia-Ju Bai Fixes: 900cca2944254edd ("lib/vsprintf: add %pC{,n,r} format specifiers for clocks") Link: http://lkml.kernel.org/r/1527845302-12159-5-git-send-email-geert+renesas@glider.be To: Jia-Ju Bai To: Jonathan Corbet To: Michael Turquette To: Stephen Boyd To: Zhang Rui To: Eduardo Valentin To: Eric Anholt To: Stefan Wahren To: Greg Kroah-Hartman Cc: Sergey Senozhatsky Cc: Petr Mladek Cc: Linus Torvalds Cc: Steven Rostedt Cc: linux-doc@vger.kernel.org Cc: linux-clk@vger.kernel.org Cc: linux-pm@vger.kernel.org Cc: linux-serial@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-renesas-soc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: Geert Uytterhoeven Cc: stable@vger.kernel.org # 4.1+ Signed-off-by: Geert Uytterhoeven Signed-off-by: Petr Mladek Signed-off-by: Greg Kroah-Hartman

lib/test_kmod.c: fix limit check on number of test devices created

2018-05-30T05:52:14+00:00

[ Upstream commit ac68b1b3b9c73e652dc7ce0585672e23c5a2dca4 ] As reported by Dan the parentheses is in the wrong place, and since unlikely() call returns either 0 or 1 it's never less than zero. The second issue is that signed integer overflows like "INT_MAX + 1" are undefined behavior. Since num_test_devs represents the number of devices, we want to stop prior to hitting the max, and not rely on the wrap arround at all. So just cap at num_test_devs + 1, prior to assigning a new device. Link: http://lkml.kernel.org/r/20180224030046.24238-1-mcgrof@kernel.org Fixes: d9c6a72d6fa2 ("kmod: add test driver to stress test the module loader") Reported-by: Dan Carpenter Signed-off-by: Luis R. Rodriguez Acked-by: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

idr: fix invalid ptr dereference on item delete

2018-05-30T05:51:49+00:00

commit 7a4deea1aa8bddfed4ef1b35fc2b6732563d8ad5 upstream. If the radix tree underlying the IDR happens to be full and we attempt to remove an id which is larger than any id in the IDR, we will call __radix_tree_delete() with an uninitialised 'slot' pointer, at which point anything could happen. This was easiest to hit with a single entry at id 0 and attempting to remove a non-0 id, but it could have happened with 64 entries and attempting to remove an id >= 64. Roman said: The syzcaller test boils down to opening /dev/kvm, creating an eventfd, and calling a couple of KVM ioctls. None of this requires superuser. And the result is dereferencing an uninitialized pointer which is likely a crash. The specific path caught by syzbot is via KVM_HYPERV_EVENTD ioctl which is new in 4.17. But I guess there are other user-triggerable paths, so cc:stable is probably justified. Matthew added: We have around 250 calls to idr_remove() in the kernel today. Many of them pass an ID which is embedded in the object they're removing, so they're safe. Picking a few likely candidates: drivers/firewire/core-cdev.c looks unsafe; the ID comes from an ioctl. drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c is similar drivers/atm/nicstar.c could be taken down by a handcrafted packet Link: http://lkml.kernel.org/r/20180518175025.GD6361@bombadil.infradead.org Fixes: 0a835c4f090a ("Reimplement IDR and IDA using the radix tree") Reported-by: Debugged-by: Roman Kagan Signed-off-by: Matthew Wilcox Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

radix tree: fix multi-order iteration race

2018-05-22T16:53:58+00:00

commit 9f418224e8114156d995b98fa4e0f4fd21f685fe upstream. Fix a race in the multi-order iteration code which causes the kernel to hit a GP fault. This was first seen with a production v4.15 based kernel (4.15.6-300.fc27.x86_64) utilizing a DAX workload which used order 9 PMD DAX entries. The race has to do with how we tear down multi-order sibling entries when we are removing an item from the tree. Remember for example that an order 2 entry looks like this: struct radix_tree_node.slots[] = [entry][sibling][sibling][sibling] where 'entry' is in some slot in the struct radix_tree_node, and the three slots following 'entry' contain sibling pointers which point back to 'entry.' When we delete 'entry' from the tree, we call : radix_tree_delete() radix_tree_delete_item() __radix_tree_delete() replace_slot() replace_slot() first removes the siblings in order from the first to the last, then at then replaces 'entry' with NULL. This means that for a brief period of time we end up with one or more of the siblings removed, so: struct radix_tree_node.slots[] = [entry][NULL][sibling][sibling] This causes an issue if you have a reader iterating over the slots in the tree via radix_tree_for_each_slot() while only under rcu_read_lock()/rcu_read_unlock() protection. This is a common case in mm/filemap.c. The issue is that when __radix_tree_next_slot() => skip_siblings() tries to skip over the sibling entries in the slots, it currently does so with an exact match on the slot directly preceding our current slot. Normally this works: V preceding slot struct radix_tree_node.slots[] = [entry][sibling][sibling][sibling] ^ current slot This lets you find the first sibling, and you skip them all in order. But in the case where one of the siblings is NULL, that slot is skipped and then our sibling detection is interrupted: V preceding slot struct radix_tree_node.slots[] = [entry][NULL][sibling][sibling] ^ current slot This means that the sibling pointers aren't recognized since they point all the way back to 'entry', so we think that they are normal internal radix tree pointers. This causes us to think we need to walk down to a struct radix_tree_node starting at the address of 'entry'. In a real running kernel this will crash the thread with a GP fault when you try and dereference the slots in your broken node starting at 'entry'. We fix this race by fixing the way that skip_siblings() detects sibling nodes. Instead of testing against the preceding slot we instead look for siblings via is_sibling_entry() which compares against the position of the struct radix_tree_node.slots[] array. This ensures that sibling entries are properly identified, even if they are no longer contiguous with the 'entry' they point to. Link: http://lkml.kernel.org/r/20180503192430.7582-6-ross.zwisler@linux.intel.com Fixes: 148deab223b2 ("radix-tree: improve multiorder iterators") Signed-off-by: Ross Zwisler Reported-by: CR, Sapthagirish Reviewed-by: Jan Kara Cc: Matthew Wilcox Cc: Christoph Hellwig Cc: Dan Williams Cc: Dave Chinner Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman