user/sven/linux.git/include/linux, branch v4.14.36

writeback: safer lock nesting

2018-04-24T07:36:39Z

commit 2e898e4c0a3897ccd434adac5abb8330194f527b upstream. lock_page_memcg()/unlock_page_memcg() use spin_lock_irqsave/restore() if the page's memcg is undergoing move accounting, which occurs when a process leaves its memcg for a new one that has memory.move_charge_at_immigrate set. unlocked_inode_to_wb_begin,end() use spin_lock_irq/spin_unlock_irq() if the given inode is switching writeback domains. Switches occur when enough writes are issued from a new domain. This existing pattern is thus suspicious: lock_page_memcg(page); unlocked_inode_to_wb_begin(inode, &locked); ... unlocked_inode_to_wb_end(inode, locked); unlock_page_memcg(page); If both inode switch and process memcg migration are both in-flight then unlocked_inode_to_wb_end() will unconditionally enable interrupts while still holding the lock_page_memcg() irq spinlock. This suggests the possibility of deadlock if an interrupt occurs before unlock_page_memcg(). truncate __cancel_dirty_page lock_page_memcg unlocked_inode_to_wb_begin unlocked_inode_to_wb_end end_page_writeback test_clear_page_writeback lock_page_memcg unlock_page_memcg Due to configuration limitations this deadlock is not currently possible because we don't mix cgroup writeback (a cgroupv2 feature) and memory.move_charge_at_immigrate (a cgroupv1 feature). If the kernel is hacked to always claim inode switching and memcg moving_account, then this script triggers lockup in less than a minute: cd /mnt/cgroup/memory mkdir a b echo 1 > a/memory.move_charge_at_immigrate echo 1 > b/memory.move_charge_at_immigrate ( echo $BASHPID > a/cgroup.procs while true; do dd if=/dev/zero of=/mnt/big bs=1M count=256 done ) & while true; do sync done & sleep 1h & SLEEP=$! while true; do echo $SLEEP > a/cgroup.procs echo $SLEEP > b/cgroup.procs done The deadlock does not seem possible, so it's debatable if there's any reason to modify the kernel. I suggest we should to prevent future surprises. And Wang Long said "this deadlock occurs three times in our environment", so there's more reason to apply this, even to stable. Stable 4.4 has minor conflicts applying this patch. For a clean 4.4 patch see "[PATCH for-4.4] writeback: safer lock nesting" https://lkml.org/lkml/2018/4/11/146 Wang Long said "this deadlock occurs three times in our environment" [gthelen@google.com: v4] Link: http://lkml.kernel.org/r/20180411084653.254724-1-gthelen@google.com [akpm@linux-foundation.org: comment tweaks, struct initialization simplification] Change-Id: Ibb773e8045852978f6207074491d262f1b3fb613 Link: http://lkml.kernel.org/r/20180410005908.167976-1-gthelen@google.com Fixes: 682aa8e1a6a1 ("writeback: implement unlocked_inode_to_wb transaction and use it for stat updates") Signed-off-by: Greg Thelen Reported-by: Wang Long Acked-by: Wang Long Acked-by: Michal Hocko Reviewed-by: Andrew Morton Cc: Johannes Weiner Cc: Tejun Heo Cc: Nicholas Piggin Cc: [v4.2+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [natechancellor: Adjust context due to lack of b93b016313b3b] Signed-off-by: Nathan Chancellor Signed-off-by: Greg Kroah-Hartman

HID: input: fix battery level reporting on BT mice

2018-04-24T07:36:37Z

commit 2e210bbb7429cdcf1a1a3ad00c1bf98bd9bf2452 upstream. The commit 581c4484769e ("HID: input: map digitizer battery usage") assumed that devices having input (qas opposed to feature) report for battery strength would report the data on their own, without the need to be polled by the kernel; unfortunately it is not so. Many wireless mice do not send unsolicited reports with battery strength data and have to be polled explicitly. As a complication, stylus devices on digitizers are not normally connected to the base and thus can not be polled - the base can only determine battery strength in the stylus when it is in proximity. To solve this issue, we add a special flag that tells the kernel to avoid polling the device (and expect unsolicited reports) and set it when report field with physical usage of digitizer stylus (HID_DG_STYLUS). Unless this flag is set, and we have not seen the unsolicited reports, the kernel will attempt to poll the device when userspace attempts to read "capacity" and "state" attributes of power_supply object corresponding to the devices battery. Fixes: 581c4484769e ("HID: input: map digitizer battery usage") Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=198095 Cc: stable@vger.kernel.org Reported-and-tested-by: Martin van Es Signed-off-by: Dmitry Torokhov Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman

block: use 32-bit blk_status_t on Alpha

2018-04-24T07:36:29Z

commit 6e2fb22103b99c26ae30a46512abe75526d8e4c9 upstream. Early alpha processors cannot write a single byte or word; they read 8 bytes, modify the value in registers and write back 8 bytes. The type blk_status_t is defined as one byte, it is often written asynchronously by I/O completion routines, this asynchronous modification can corrupt content of nearby bytes if these nearby bytes can be written simultaneously by another CPU. - one example of such corruption is the structure dm_io where "blk_status_t status" is written by an asynchronous completion routine and "atomic_t io_count" is modified synchronously - another example is the structure dm_buffer where "unsigned hold_count" is modified synchronously from process context and "blk_status_t write_error" is modified asynchronously from bio completion routine This patch fixes the bug by changing the type blk_status_t to 32 bits if we are on Alpha and if we are compiling for a processor that doesn't have the byte-word-extension. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org # 4.13+ Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

HID: core: Fix size as type u32

2018-04-24T07:36:28Z

commit 6de0b13cc0b4ba10e98a9263d7a83b940720b77a upstream. When size is negative, calling memset will make segment fault. Declare the size as type u32 to keep memset safe. size in struct hid_report is unsigned, fix return type of hid_report_len to u32. Cc: stable@vger.kernel.org Signed-off-by: Aaron Ma Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman

task_struct: only use anon struct under randstruct plugin

2018-04-24T07:36:22Z

commit 2cfe0d3009418a132b93d78642a8059a38fe5944 upstream. The original intent for always adding the anonymous struct in task_struct was to make sure we had compiler coverage. However, this caused pathological padding of 40 bytes at the start of task_struct. Instead, move the anonymous struct to being only used when struct layout randomization is enabled. Link: http://lkml.kernel.org/r/20180327213609.GA2964@beast Fixes: 29e48ce87f1e ("task_struct: Allow randomized") Signed-off-by: Kees Cook Reported-by: Peter Zijlstra Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm/hmm: fix header file if/else/endif maze

2018-04-24T07:36:22Z

commit b28b08de436a638c82d0cf3dcdbdbad055baf1fc upstream. The #if/#else/#endif for IS_ENABLED(CONFIG_HMM) were wrong. Because of this after multiple include there was multiple definition of both hmm_mm_init() and hmm_mm_destroy() leading to build failure if HMM was enabled (CONFIG_HMM set). Link: http://lkml.kernel.org/r/20180323005527.758-3-jglisse@redhat.com Signed-off-by: Jérôme Glisse Acked-by: Balbir Singh Cc: Andrew Morton Cc: Ralph Campbell Cc: John Hubbard Cc: Evgeny Baskakov Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

tty: make n_tty_read() always abort if hangup is in progress

2018-04-24T07:36:21Z

commit 28b0f8a6962a24ed21737578f3b1b07424635c9e upstream. A tty is hung up by __tty_hangup() setting file->f_op to hung_up_tty_fops, which is skipped on ttys whose write operation isn't tty_write(). This means that, for example, /dev/console whose write op is redirected_tty_write() is never actually marked hung up. Because n_tty_read() uses the hung up status to decide whether to abort the waiting readers, the lack of hung-up marking can lead to the following scenario. 1. A session contains two processes. The leader and its child. The child ignores SIGHUP. 2. The leader exits and starts disassociating from the controlling terminal (/dev/console). 3. __tty_hangup() skips setting f_op to hung_up_tty_fops. 4. SIGHUP is delivered and ignored. 5. tty_ldisc_hangup() is invoked. It wakes up the waits which should clear the read lockers of tty->ldisc_sem. 6. The reader wakes up but because tty_hung_up_p() is false, it doesn't abort and goes back to sleep while read-holding tty->ldisc_sem. 7. The leader progresses to tty_ldisc_lock() in tty_ldisc_hangup() and is now stuck in D sleep indefinitely waiting for tty->ldisc_sem. The following is Alan's explanation on why some ttys aren't hung up. http://lkml.kernel.org/r/20171101170908.6ad08580@alans-desktop 1. It broke the serial consoles because they would hang up and close down the hardware. With tty_port that *should* be fixable properly for any cases remaining. 2. The console layer was (and still is) completely broken and doens't refcount properly. So if you turn on console hangups it breaks (as indeed does freeing consoles and half a dozen other things). As neither can be fixed quickly, this patch works around the problem by introducing a new flag, TTY_HUPPING, which is used solely to tell n_tty_read() that hang-up is in progress for the console and the readers should be aborted regardless of the hung-up status of the device. The following is a sample hung task warning caused by this issue. INFO: task agetty:2662 blocked for more than 120 seconds. Not tainted 4.11.3-dbg-tty-lockup-02478-gfd6c7ee-dirty #28 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. 0 2662 1 0x00000086 Call Trace: __schedule+0x267/0x890 schedule+0x36/0x80 schedule_timeout+0x23c/0x2e0 ldsem_down_write+0xce/0x1f6 tty_ldisc_lock+0x16/0x30 tty_ldisc_hangup+0xb3/0x1b0 __tty_hangup+0x300/0x410 disassociate_ctty+0x6c/0x290 do_exit+0x7ef/0xb00 do_group_exit+0x3f/0xa0 get_signal+0x1b3/0x5d0 do_signal+0x28/0x660 exit_to_usermode_loop+0x46/0x86 do_syscall_64+0x9c/0xb0 entry_SYSCALL64_slow_path+0x25/0x25 The following is the repro. Run "$PROG /dev/console". The parent process hangs in D state. #include #include #include #include #include #include #include #include #include #include #include #include int main(int argc, char **argv) { struct sigaction sact = { .sa_handler = SIG_IGN }; struct timespec ts1s = { .tv_sec = 1 }; pid_t pid; int fd; if (argc < 2) { fprintf(stderr, "test-hung-tty /dev/$TTY\n"); return 1; } /* fork a child to ensure that it isn't already the session leader */ pid = fork(); if (pid < 0) { perror("fork"); return 1; } if (pid > 0) { /* top parent, wait for everyone */ while (waitpid(-1, NULL, 0) >= 0) ; if (errno != ECHILD) perror("waitpid"); return 0; } /* new session, start a new session and set the controlling tty */ if (setsid() < 0) { perror("setsid"); return 1; } fd = open(argv[1], O_RDWR); if (fd < 0) { perror("open"); return 1; } if (ioctl(fd, TIOCSCTTY, 1) < 0) { perror("ioctl"); return 1; } /* fork a child, sleep a bit and exit */ pid = fork(); if (pid < 0) { perror("fork"); return 1; } if (pid > 0) { nanosleep(&ts1s, NULL); printf("Session leader exiting\n"); exit(0); } /* * The child ignores SIGHUP and keeps reading from the controlling * tty. Because SIGHUP is ignored, the child doesn't get killed on * parent exit and the bug in n_tty makes the read(2) block the * parent's control terminal hangup attempt. The parent ends up in * D sleep until the child is explicitly killed. */ sigaction(SIGHUP, &sact, NULL); printf("Child reading tty\n"); while (1) { char buf[1024]; if (read(fd, buf, sizeof(buf)) < 0) { perror("read"); return 1; } } return 0; } Signed-off-by: Tejun Heo Cc: Alan Cox Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

net/mlx5: Fix race for multiple RoCE enable

2018-04-12T10:32:17Z

[ Upstream commit 734dc065fc41f6143ff88225aa5d335cb1e0f6aa ] There are two potential problems with the existing implementation. 1. Enable and disable can race after the atomic operations. 2. If a command fails the refcount is left in an inconsistent state. Introduce a lock and perform error checking. Fixes: a6f7d2aff623 ("net/mlx5: Add support for multiple RoCE enable") Signed-off-by: Daniel Jurgens Reviewed-by: Parav Pandit Signed-off-by: Leon Romanovsky Signed-off-by: Jason Gunthorpe Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

clk: divider: fix incorrect usage of container_of

2018-04-12T10:32:13Z

[ Upstream commit 12a26c298d2a8b1cab498533fa65198e49e3afd3 ] divider_recalc_rate() is an helper function used by clock divider of different types, so the structure containing the 'hw' pointer is not always a 'struct clk_divider' At the following line: > div = _get_div(table, val, flags, divider->width); in several cases, the value of 'divider->width' is garbage as the actual structure behind this memory is not a 'struct clk_divider' Fortunately, this width value is used by _get_val() only when CLK_DIVIDER_MAX_AT_ZERO flag is set. This has never been the case so far when the structure is not a 'struct clk_divider'. This is probably why we did not notice this bug before Fixes: afe76c8fd030 ("clk: allow a clk divider with max divisor when zero") Signed-off-by: Jerome Brunet Acked-by: Alexandre Belloni Acked-by: Sylvain Lemieux Signed-off-by: Stephen Boyd Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

bitmap: fix memset optimization on big-endian systems

2018-04-08T12:26:30Z

commit 21035965f60b0502fc6537b232839389bb4ce664 upstream. Commit 2a98dc028f91 ("include/linux/bitmap.h: turn bitmap_set and bitmap_clear into memset when possible") introduced an optimization to bitmap_{set,clear}() which uses memset() when the start and length are constants aligned to a byte. This is wrong on big-endian systems; our bitmaps are arrays of unsigned long, so bit n is not at byte n / 8 in memory. This was caught by the Btrfs selftests, but the bitmap selftests also fail when run on a big-endian machine. We can still use memset if the start and length are aligned to an unsigned long, so do that on big-endian. The same problem applies to the memcmp in bitmap_equal(), so fix it there, too. Fixes: 2a98dc028f91 ("include/linux/bitmap.h: turn bitmap_set and bitmap_clear into memset when possible") Fixes: 2c6deb01525a ("bitmap: use memcmp optimisation in more situations") Cc: stable@kernel.org Reported-by: "Erhard F." Cc: Matthew Wilcox Cc: Rasmus Villemoes Cc: Andrew Morton Cc: Arnd Bergmann Signed-off-by: Omar Sandoval Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman