From: Anders Roxell anders.roxell@linaro.org

[ Upstream commit 347a28b586802d09604a149c1a1f6de5dccbe6fa ]

This happened while running in qemu-system-aarch64, the AMBA PL011 UART driver when enabling CONFIG_DEBUG_TEST_DRIVER_REMOVE. arch_initcall(pl011_init) came before subsys_initcall(default_bdi_init), devtmpfs' handle_remove() crashes because the reference count is a NULL pointer only because wb->bdi hasn't been initialized yet.

Rework so that wb_put have an extra check if wb->bdi before decrement wb->refcnt and also add a WARN_ON_ONCE to get a warning if it happens again in other drivers.

Fixes: 52ebea749aae ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks") Co-developed-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Anders Roxell anders.roxell@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/backing-dev-defs.h | 8 ++++++++ 1 file changed, 8 insertions(+)

diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index 32728ff8095c..4ea779b25a51 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -225,6 +225,14 @@ static inline void wb_get(struct bdi_writeback *wb) */ static inline void wb_put(struct bdi_writeback *wb) { + if (WARN_ON_ONCE(!wb->bdi)) { + /* + * A driver bug might cause a file to be removed before bdi was + * initialized. + */ + return; + } + if (wb != &wb->bdi->wb) percpu_ref_put(&wb->refcnt); }

From: Takashi Sakamoto o-takashi@sakamocchi.jp

[ Upstream commit fba43f454cdf9caa3185219d116bd2a6e6354552 ]

This commit adds support for APOGEE duet FireWire, launched 2007, already discontinued. This model uses Oxford Semiconductor FW971 as its communication engine. Below is information on Configuration ROM of this unit. The unit supports some AV/C commands defined by Audio subunit specification and vendor dependent commands.

$ ./hinawa-config-rom-printer /dev/fw1 { 'bus-info': { 'adj': False, 'bmc': False, 'chip_ID': 42949742248, 'cmc': False, 'cyc_clk_acc': 255, 'generation': 0, 'imc': False, 'isc': True, 'link_spd': 3, 'max_ROM': 0, 'max_rec': 64, 'name': '1394', 'node_vendor_ID': 987, 'pmc': False}, 'root-directory': [ ['VENDOR', 987], ['DESCRIPTOR', 'Apogee Electronics'], ['MODEL', 122333], ['DESCRIPTOR', 'Duet'], [ 'NODE_CAPABILITIES', { 'addressing': {'64': True, 'fix': True, 'prv': False}, 'misc': {'int': False, 'ms': False, 'spt': True}, 'state': { 'atn': False, 'ded': False, 'drq': True, 'elo': False, 'init': False, 'lst': True, 'off': False}, 'testing': {'bas': False, 'ext': False}}], [ 'UNIT', [ ['SPECIFIER_ID', 41005], ['VERSION', 65537], ['MODEL', 122333], ['DESCRIPTOR', 'Duet']]]]}

Signed-off-by: Takashi Sakamoto o-takashi@sakamocchi.jp Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- sound/firewire/Kconfig | 1 + sound/firewire/oxfw/oxfw.c | 8 ++++++++ 2 files changed, 9 insertions(+)

diff --git a/sound/firewire/Kconfig b/sound/firewire/Kconfig index ab894ed1ff67..8557e54d2659 100644 --- a/sound/firewire/Kconfig +++ b/sound/firewire/Kconfig @@ -40,6 +40,7 @@ config SND_OXFW * Mackie(Loud) U.420/U.420d * TASCAM FireOne * Stanton Controllers & Systems 1 Deck/Mixer + * APOGEE duet FireWire

To compile this driver as a module, choose M here: the module will be called snd-oxfw. diff --git a/sound/firewire/oxfw/oxfw.c b/sound/firewire/oxfw/oxfw.c index 696b6cf35003..b0395c4209ab 100644 --- a/sound/firewire/oxfw/oxfw.c +++ b/sound/firewire/oxfw/oxfw.c @@ -20,6 +20,7 @@ #define VENDOR_LACIE 0x00d04b #define VENDOR_TASCAM 0x00022e #define OUI_STANTON 0x001260 +#define OUI_APOGEE 0x0003db

#define MODEL_SATELLITE 0x00200f

@@ -441,6 +442,13 @@ static const struct ieee1394_device_id oxfw_id_table[] = { .vendor_id = OUI_STANTON, .model_id = 0x002000, }, + // APOGEE, duet FireWire + { + .match_flags = IEEE1394_MATCH_VENDOR_ID | + IEEE1394_MATCH_MODEL_ID, + .vendor_id = OUI_APOGEE, + .model_id = 0x01dddd, + }, { } }; MODULE_DEVICE_TABLE(ieee1394, oxfw_id_table);

From: Anders Roxell anders.roxell@linaro.org

[ Upstream commit 81e9fa8bab381f8b6eb04df7cdf0f71994099bd4 ]

The armv8_pmuv3 driver doesn't have a remove function, and when the test 'CONFIG_DEBUG_TEST_DRIVER_REMOVE=y' is enabled, the following Call trace can be seen.

[ 1.424287] Failed to register pmu: armv8_pmuv3, reason -17 [ 1.424870] WARNING: CPU: 0 PID: 1 at ../kernel/events/core.c:11771 perf_event_sysfs_init+0x98/0xdc [ 1.425220] Modules linked in: [ 1.425531] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 4.19.0-rc7-next-20181012-00003-ge7a97b1ad77b-dirty #35 [ 1.425951] Hardware name: linux,dummy-virt (DT) [ 1.426212] pstate: 80000005 (Nzcv daif -PAN -UAO) [ 1.426458] pc : perf_event_sysfs_init+0x98/0xdc [ 1.426720] lr : perf_event_sysfs_init+0x98/0xdc [ 1.426908] sp : ffff00000804bd50 [ 1.427077] x29: ffff00000804bd50 x28: ffff00000934e078 [ 1.427429] x27: ffff000009546000 x26: 0000000000000007 [ 1.427757] x25: ffff000009280710 x24: 00000000ffffffef [ 1.428086] x23: ffff000009408000 x22: 0000000000000000 [ 1.428415] x21: ffff000009136008 x20: ffff000009408730 [ 1.428744] x19: ffff80007b20b400 x18: 000000000000000a [ 1.429075] x17: 0000000000000000 x16: 0000000000000000 [ 1.429418] x15: 0000000000000400 x14: 2e79726f74636572 [ 1.429748] x13: 696420656d617320 x12: 656874206e692065 [ 1.430060] x11: 6d616e20656d6173 x10: 2065687420687469 [ 1.430335] x9 : ffff00000804bd50 x8 : 206e6f7361657220 [ 1.430610] x7 : 2c3376756d705f38 x6 : ffff00000954d7ce [ 1.430880] x5 : 0000000000000000 x4 : 0000000000000000 [ 1.431226] x3 : 0000000000000000 x2 : ffffffffffffffff [ 1.431554] x1 : 4d151327adc50b00 x0 : 0000000000000000 [ 1.431868] Call trace: [ 1.432102] perf_event_sysfs_init+0x98/0xdc [ 1.432382] do_one_initcall+0x6c/0x1a8 [ 1.432637] kernel_init_freeable+0x1bc/0x280 [ 1.432905] kernel_init+0x18/0x160 [ 1.433115] ret_from_fork+0x10/0x18 [ 1.433297] ---[ end trace 27fd415390eb9883 ]---

Rework to set suppress_bind_attrs flag to avoid removing the device when CONFIG_DEBUG_TEST_DRIVER_REMOVE=y, since there's no real reason to remove the armv8_pmuv3 driver.

Cc: Arnd Bergmann arnd@arndb.de Co-developed-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Anders Roxell anders.roxell@linaro.org Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/kernel/perf_event.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index 199a23f058d5..0770d6d1c37f 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -1114,6 +1114,7 @@ static struct platform_driver armv8_pmu_driver = { .driver = { .name = ARMV8_PMU_PDEV_NAME, .of_match_table = armv8_pmu_of_device_ids, + .suppress_bind_attrs = true, }, .probe = armv8_pmu_device_probe, };

From: Ondrej Mosnacek omosnace@redhat.com

[ Upstream commit 2cbdcb882f97a45f7475c67ac6257bbc16277dfe ]

If a superblock has the MS_SUBMOUNT flag set, we should always allow mounting it. These mounts are done automatically by the kernel either as part of mounting some parent mount (e.g. debugfs always mounts tracefs under "tracing" for compatibility) or they are mounted automatically as needed on subdirectory accesses (e.g. NFS crossmnt mounts). Since such automounts are either an implicit consequence of the parent mount (which is already checked) or they can happen during regular accesses (where it doesn't make sense to check against the current task's context), the mount permission check should be skipped for them.

Without this patch, attempts to access contents of an automounted directory can cause unexpected SELinux denials.

In the current kernel tree, the MS_SUBMOUNT flag is set only via vfs_submount(), which is called only from the following places: - AFS, when automounting special "symlinks" referencing other cells - CIFS, when automounting "referrals" - NFS, when automounting subtrees - debugfs, when automounting tracefs

In all cases the submounts are meant to be transparent to the user and it makes sense that if mounting the master is allowed, then so should be the automounts. Note that CAP_SYS_ADMIN capability checking is already skipped for (SB_KERNMOUNT|SB_SUBMOUNT) in: - sget_userns() in fs/super.c: if (!(flags & (SB_KERNMOUNT|SB_SUBMOUNT)) && !(type->fs_flags & FS_USERNS_MOUNT) && !capable(CAP_SYS_ADMIN)) return ERR_PTR(-EPERM); - sget() in fs/super.c: /* Ensure the requestor has permissions over the target filesystem */ if (!(flags & (SB_KERNMOUNT|SB_SUBMOUNT)) && !ns_capable(user_ns, CAP_SYS_ADMIN)) return ERR_PTR(-EPERM);

Verified internally on patched RHEL 7.6 with a reproducer using NFS+httpd and selinux-tesuite.

Fixes: 93faccbbfa95 ("fs: Better permission checking for submounts") Signed-off-by: Ondrej Mosnacek omosnace@redhat.com Signed-off-by: Paul Moore paul@paul-moore.com Signed-off-by: Sasha Levin sashal@kernel.org --- security/selinux/hooks.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 8ded80867b92..d293b546a2aa 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2758,7 +2758,7 @@ static int selinux_sb_kern_mount(struct super_block *sb, int flags, void *data) return rc;

/* Allow all mounts performed by the kernel */ - if (flags & MS_KERNMOUNT) + if (flags & (MS_KERNMOUNT | MS_SUBMOUNT)) return 0;

ad.type = LSM_AUDIT_DATA_DENTRY;

From: Chuck Lever chuck.lever@oracle.com

[ Upstream commit b024dd0eba6e6d568f69d63c5e3153aba94c23e3 ]

FRWR memory registration is done with a series of calls and WRs. 1. ULP invokes ib_dma_map_sg() 2. ULP invokes ib_map_mr_sg() 3. ULP posts an IB_WR_REG_MR on the Send queue

Step 2 generates an iova. It is permissible for ULPs to change this iova (with certain restrictions) between steps 2 and 3.

rxe_map_mr_sg captures the MR's iova but later when rxe processes the REG_MR WR, it ignores the MR's iova field. If a ULP alters the MR's iova after step 2 but before step 3, rxe never captures that change.

When the remote sends an RDMA Read targeting that MR, rxe looks up the R_key, but the altered iova does not match the iova stored in the MR, causing the RDMA Read request to fail.

Reported-by: Anna Schumaker schumaker.anna@gmail.com Signed-off-by: Chuck Lever chuck.lever@oracle.com Reviewed-by: Sagi Grimberg sagi@grimberg.me Signed-off-by: Jason Gunthorpe jgg@mellanox.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/infiniband/sw/rxe/rxe_req.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/drivers/infiniband/sw/rxe/rxe_req.c b/drivers/infiniband/sw/rxe/rxe_req.c index 47219ebd8ff2..0f9fe2ca2a91 100644 --- a/drivers/infiniband/sw/rxe/rxe_req.c +++ b/drivers/infiniband/sw/rxe/rxe_req.c @@ -643,6 +643,7 @@ int rxe_requester(void *arg) rmr->access = wqe->wr.wr.reg.access; rmr->lkey = wqe->wr.wr.reg.key; rmr->rkey = wqe->wr.wr.reg.key; + rmr->iova = wqe->wr.wr.reg.mr->iova; wqe->state = wqe_state_done; wqe->status = IB_WC_SUCCESS; } else {

From: "Joel Fernandes (Google)" joel@joelfernandes.org

[ Upstream commit 30696378f68a9e3dad6bfe55938b112e72af00c2 ]

The ramoops backend currently calls persistent_ram_save_old() even if a buffer is empty. While this appears to work, it is does not seem like the right thing to do and could lead to future bugs so lets avoid that. It also prevents misleading prints in the logs which claim the buffer is valid.

I got something like:

found existing buffer, size 0, start 0

When I was expecting:

no valid data in buffer (sig = ...)

This bails out early (and reports with pr_debug()), since it's an acceptable state.

Signed-off-by: Joel Fernandes (Google) joel@joelfernandes.org Co-developed-by: Kees Cook keescook@chromium.org Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/pstore/ram_core.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c index ecdb3baa1283..11e558efd61e 100644 --- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -488,6 +488,11 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig, sig ^= PERSISTENT_RAM_SIG;

if (prz->buffer->sig == sig) { + if (buffer_size(prz) == 0) { + pr_debug("found existing empty buffer\n"); + return 0; + } + if (buffer_size(prz) > prz->buffer_size || buffer_start(prz) > buffer_size(prz)) pr_info("found existing invalid buffer, size %zu, start %zu\n",

From: Breno Leitao leitao@debian.org

[ Upstream commit 2b038cbc5fcf12a7ee1cc9bfd5da1e46dacdee87 ]

When booting a pseries kernel with PREEMPT enabled, it dumps the following warning:

BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1 caller is pseries_processor_idle_init+0x5c/0x22c CPU: 13 PID: 1 Comm: swapper/0 Not tainted 4.20.0-rc3-00090-g12201a0128bc-dirty #828 Call Trace: [c000000429437ab0] [c0000000009c8878] dump_stack+0xec/0x164 (unreliable) [c000000429437b00] [c0000000005f2f24] check_preemption_disabled+0x154/0x160 [c000000429437b90] [c000000000cab8e8] pseries_processor_idle_init+0x5c/0x22c [c000000429437c10] [c000000000010ed4] do_one_initcall+0x64/0x300 [c000000429437ce0] [c000000000c54500] kernel_init_freeable+0x3f0/0x500 [c000000429437db0] [c0000000000112dc] kernel_init+0x2c/0x160 [c000000429437e20] [c00000000000c1d0] ret_from_kernel_thread+0x5c/0x6c

This happens because the code calls get_lppaca() which calls get_paca() and it checks if preemption is disabled through check_preemption_disabled().

Preemption should be disabled because the per CPU variable may make no sense if there is a preemption (and a CPU switch) after it reads the per CPU data and when it is used.

In this device driver specifically, it is not a problem, because this code just needs to have access to one lppaca struct, and it does not matter if it is the current per CPU lppaca struct or not (i.e. when there is a preemption and a CPU migration).

That said, the most appropriate fix seems to be related to avoiding the debug_smp_processor_id() call at get_paca(), instead of calling preempt_disable() before get_paca().

Signed-off-by: Breno Leitao leitao@debian.org Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/cpuidle/cpuidle-pseries.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/cpuidle/cpuidle-pseries.c b/drivers/cpuidle/cpuidle-pseries.c index 166ccd711ec9..83203c59bf59 100644 --- a/drivers/cpuidle/cpuidle-pseries.c +++ b/drivers/cpuidle/cpuidle-pseries.c @@ -230,7 +230,13 @@ static int pseries_idle_probe(void) return -ENODEV;

if (firmware_has_feature(FW_FEATURE_SPLPAR)) { - if (lppaca_shared_proc(get_lppaca())) { + /* + * Use local_paca instead of get_lppaca() since + * preemption is not disabled, and it is not required in + * fact, since lppaca_ptr does not need to be the value + * associated to the current CPU, it can be from any CPU. + */ + if (lppaca_shared_proc(local_paca->lppaca_ptr)) { cpuidle_state_table = shared_states; max_idle_state = ARRAY_SIZE(shared_states); } else {

From: yupeng yupeng0921@gmail.com

[ Upstream commit 0fbe82e628c817e292ff588cd5847fc935e025f2 ]

after set SO_DONTROUTE to 1, the IP layer should not route packets if the dest IP address is not in link scope. But if the socket has cached the dst_entry, such packets would be routed until the sk_dst_cache expires. So we should clean the sk_dst_cache when a user set SO_DONTROUTE option. Below are server/client python scripts which could reprodue this issue:

server side code:

========================================================================== import socket import struct import time

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.bind(('0.0.0.0', 9000)) s.listen(1) sock, addr = s.accept() sock.setsockopt(socket.SOL_SOCKET, socket.SO_DONTROUTE, struct.pack('i', 1)) while True: sock.send(b'foo') time.sleep(1) ==========================================================================

client side code: ========================================================================== import socket import time

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect(('server_address', 9000)) while True: data = s.recv(1024) print(data) ==========================================================================

Signed-off-by: yupeng yupeng0921@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/sock.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/net/core/sock.c b/net/core/sock.c index 1c4c43483b54..8566da877ec2 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -699,6 +699,7 @@ int sock_setsockopt(struct socket *sock, int level, int optname, break; case SO_DONTROUTE: sock_valbool_flag(sk, SOCK_LOCALROUTE, valbool); + sk_dst_reset(sk); break; case SO_BROADCAST: sock_valbool_flag(sk, SOCK_BROADCAST, valbool);

From: Lucas Stach l.stach@pengutronix.de

[ Upstream commit f7542d817733f461258fd3a47d77da35b2d9fc81 ]

The exclusive gates may be set up in the wrong way by software running before the clock driver comes up. In that case the exclusive setup is locked in its initial state, as the complementary function can't be activated without disabling the initial setup first.

To avoid this lock situation, reset the exclusive gates to the off state and allow the kernel to provide the proper setup.

Signed-off-by: Lucas Stach l.stach@pengutronix.de Reviewed-by: Dong Aisheng Aisheng.dong@nxp.com Signed-off-by: Stephen Boyd sboyd@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/clk/imx/clk-imx6q.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/imx/clk-imx6q.c b/drivers/clk/imx/clk-imx6q.c index 93a19667003d..14682df5d312 100644 --- a/drivers/clk/imx/clk-imx6q.c +++ b/drivers/clk/imx/clk-imx6q.c @@ -258,8 +258,12 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node) * lvds1_gate and lvds2_gate are pseudo-gates. Both can be * independently configured as clock inputs or outputs. We treat * the "output_enable" bit as a gate, even though it's really just - * enabling clock output. + * enabling clock output. Initially the gate bits are cleared, as + * otherwise the exclusive configuration gets locked in the setup done + * by software running before the clock driver, with no way to change + * it. */ + writel(readl(base + 0x160) & ~0x3c00, base + 0x160); clk[IMX6QDL_CLK_LVDS1_GATE] = imx_clk_gate_exclusive("lvds1_gate", "lvds1_sel", base + 0x160, 10, BIT(12)); clk[IMX6QDL_CLK_LVDS2_GATE] = imx_clk_gate_exclusive("lvds2_gate", "lvds2_sel", base + 0x160, 11, BIT(13));

From: Masahiro Yamada yamada.masahiro@socionext.com

[ Upstream commit fbac5977d81cb2b2b7e37b11c459055d9585273c ]

An unterminated string literal followed by new line is passed to the parser (with "multi-line strings not supported" warning shown), then handled properly there.

On the other hand, an unterminated string literal at end of file is never passed to the parser, then results in memory leak.

[Test Code]

----------(Kconfig begin)---------- source "Kconfig.inc"

config A bool "a" -----------(Kconfig end)-----------

--------(Kconfig.inc begin)-------- config B bool "b\No new line at end of file ---------(Kconfig.inc end)---------

[Summary from Valgrind]

Before the fix:

LEAK SUMMARY: definitely lost: 16 bytes in 1 blocks ...

After the fix:

LEAK SUMMARY: definitely lost: 0 bytes in 0 blocks ...

Eliminate the memory leak path by handling this case. Of course, such a Kconfig file is wrong already, so I will add an error message later.

Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com Signed-off-by: Sasha Levin sashal@kernel.org --- scripts/kconfig/zconf.l | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/scripts/kconfig/zconf.l b/scripts/kconfig/zconf.l index 6534dc5ac803..0c7800112ff5 100644 --- a/scripts/kconfig/zconf.l +++ b/scripts/kconfig/zconf.l @@ -191,6 +191,8 @@ n [A-Za-z0-9_-] } <<EOF>> { BEGIN(INITIAL); + yylval.string = text; + return T_WORD_QUOTE; } }

From: Sergey Senozhatsky sergey.senozhatsky.work@gmail.com

[ Upstream commit d72402145ace0697a6a9e8e75a3de5bf3375f78d ]

LKP has hit yet another circular locking dependency between uart console drivers and debugobjects [1]:

CPU0 CPU1

rhltable_init() __init_work() debug_object_init uart_shutdown() /* db->lock */ /* uart_port->lock */ debug_print_object() free_page() printk() call_console_drivers() debug_check_no_obj_freed() /* uart_port->lock */ /* db->lock */ debug_print_object()

So there are two dependency chains: uart_port->lock -> db->lock And db->lock -> uart_port->lock

This particular circular locking dependency can be addressed in several ways:

a) One way would be to move debug_print_object() out of db->lock scope and, thus, break the db->lock -> uart_port->lock chain. b) Another one would be to free() transmit buffer page out of db->lock in UART code; which is what this patch does.

It makes sense to apply a) and b) independently: there are too many things going on behind free(), none of which depend on uart_port->lock.

The patch fixes transmit buffer page free() in uart_shutdown() and, additionally, in uart_port_startup() (as was suggested by Dmitry Safonov).

[1] https://lore.kernel.org/lkml/20181211091154.GL23332@shao2-debian/T/#u Signed-off-by: Sergey Senozhatsky sergey.senozhatsky@gmail.com Reviewed-by: Petr Mladek pmladek@suse.com Acked-by: Peter Zijlstra (Intel) peterz@infradead.org Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Jiri Slaby jslaby@suse.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Waiman Long longman@redhat.com Cc: Dmitry Safonov dima@arista.com Cc: Steven Rostedt rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/serial_core.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 53e6db8b0330..bcfdaf6ddbb2 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -195,10 +195,15 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, if (!state->xmit.buf) { state->xmit.buf = (unsigned char *) page; uart_circ_clear(&state->xmit); + uart_port_unlock(uport, flags); } else { + uart_port_unlock(uport, flags); + /* + * Do not free() the page under the port lock, see + * uart_shutdown(). + */ free_page(page); } - uart_port_unlock(uport, flags);

retval = uport->ops->startup(uport); if (retval == 0) { @@ -258,6 +263,7 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state) struct uart_port *uport = uart_port_check(state); struct tty_port *port = &state->port; unsigned long flags = 0; + char *xmit_buf = NULL;

/* * Set the TTY IO error marker @@ -288,14 +294,18 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state) tty_port_set_suspended(port, 0);

/* - * Free the transmit buffer page. + * Do not free() the transmit buffer page under the port lock since + * this can create various circular locking scenarios. For instance, + * console driver may need to allocate/free a debug object, which + * can endup in printk() recursion. */ uart_port_lock(state, flags); - if (state->xmit.buf) { - free_page((unsigned long)state->xmit.buf); - state->xmit.buf = NULL; - } + xmit_buf = state->xmit.buf; + state->xmit.buf = NULL; uart_port_unlock(uport, flags); + + if (xmit_buf) + free_page((unsigned long)xmit_buf); }

/**

From: Arnaldo Carvalho de Melo acme@redhat.com

[ Upstream commit 2f5302533f306d5ee87bd375aef9ca35b91762cb ]

The strncpy() function may leave the destination string buffer unterminated, better use strlcpy() that we have a __weak fallback implementation for systems without it.

In this specific case this would only happen if fgets() was buggy, as its man page states that it should read one less byte than the size of the destination buffer, so that it can put the nul byte at the end of it, so it would never copy 255 non-nul chars, as fgets reads into the orig buffer at most 254 non-nul chars and terminates it. But lets just switch to strlcpy to keep the original intent and silence the gcc 8.2 warning.

This fixes this warning on an Alpine Linux Edge system with gcc 8.2:

In function 'cpu_model', inlined from 'svg_cpu_box' at util/svghelper.c:378:2: util/svghelper.c:337:5: error: 'strncpy' output may be truncated copying 255 bytes from a string of length 255 [-Werror=stringop-truncation] strncpy(cpu_m, &buf[13], 255); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Cc: Adrian Hunter adrian.hunter@intel.com Cc: Jiri Olsa jolsa@kernel.org Cc: Namhyung Kim namhyung@kernel.org Cc: Arjan van de Ven arjan@linux.intel.com Fixes: f48d55ce7871 ("perf: Add a SVG helper library file") Link: https://lkml.kernel.org/n/tip-xzkoo0gyr56gej39ltivuh9g@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/util/svghelper.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/svghelper.c b/tools/perf/util/svghelper.c index 1cbada2dc6be..f735ee038713 100644 --- a/tools/perf/util/svghelper.c +++ b/tools/perf/util/svghelper.c @@ -334,7 +334,7 @@ static char *cpu_model(void) if (file) { while (fgets(buf, 255, file)) { if (strstr(buf, "model name")) { - strncpy(cpu_m, &buf[13], 255); + strlcpy(cpu_m, &buf[13], 255); break; } }

From: Nikos Tsironis ntsironis@arrikto.com

[ Upstream commit d7e6b8dfc7bcb3f4f3a18313581f67486a725b52 ]

When using kcopyd to run callbacks through dm_kcopyd_do_callback() or submitting copy jobs with a source size of 0, the jobs are pushed directly to the complete_jobs list, which could be under processing by the kcopyd thread. As a result, the kcopyd thread can continue running completed jobs indefinitely, without releasing the CPU, as long as someone keeps submitting new completed jobs through the aforementioned paths. Processing of work items, queued for execution on the same CPU as the currently running kcopyd thread, is thus stalled for excessive amounts of time, hurting performance.

Running the following test, from the device mapper test suite [1],

dmtest run --suite snapshot -n parallel_io_to_many_snaps_N

, with 8 active snapshots, we get, in dmesg, messages like the following:

[68899.948523] BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 95s! [68899.949282] Showing busy workqueues and worker pools: [68899.949288] workqueue events: flags=0x0 [68899.949295] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256 [68899.949306] pending: vmstat_shepherd, cache_reap [68899.949331] workqueue mm_percpu_wq: flags=0x8 [68899.949337] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256 [68899.949345] pending: vmstat_update [68899.949387] workqueue dm_bufio_cache: flags=0x8 [68899.949392] pwq 4: cpus=2 node=0 flags=0x0 nice=0 active=1/256 [68899.949400] pending: work_fn [dm_bufio] [68899.949423] workqueue kcopyd: flags=0x8 [68899.949429] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256 [68899.949437] pending: do_work [dm_mod] [68899.949452] workqueue kcopyd: flags=0x8 [68899.949458] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256 [68899.949466] in-flight: 13:do_work [dm_mod] [68899.949474] pending: do_work [dm_mod] [68899.949487] workqueue kcopyd: flags=0x8 [68899.949493] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256 [68899.949501] pending: do_work [dm_mod] [68899.949515] workqueue kcopyd: flags=0x8 [68899.949521] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256 [68899.949529] pending: do_work [dm_mod] [68899.949541] workqueue kcopyd: flags=0x8 [68899.949547] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256 [68899.949555] pending: do_work [dm_mod] [68899.949568] pool 0: cpus=0 node=0 flags=0x0 nice=0 hung=95s workers=4 idle: 27130 27223 1084

Fix this by splitting the complete_jobs list into two parts: A user facing part, named callback_jobs, and one used internally by kcopyd, retaining the name complete_jobs. dm_kcopyd_do_callback() and dispatch_job() now push their jobs to the callback_jobs list, which is spliced to the complete_jobs list once, every time the kcopyd thread wakes up. This prevents kcopyd from hogging the CPU indefinitely and causing workqueue stalls.

Re-running the aforementioned test:

* Workqueue stalls are eliminated * The maximum writing time among all targets is reduced from 09m37.10s to 06m04.85s and the total run time of the test is reduced from 10m43.591s to 7m19.199s

[1] https://github.com/jthornber/device-mapper-test-suite

Signed-off-by: Nikos Tsironis ntsironis@arrikto.com Signed-off-by: Ilias Tsitsimpis iliastsi@arrikto.com Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/dm-kcopyd.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c index 56fcccc30554..e0cfde3501e0 100644 --- a/drivers/md/dm-kcopyd.c +++ b/drivers/md/dm-kcopyd.c @@ -55,15 +55,17 @@ struct dm_kcopyd_client { struct dm_kcopyd_throttle *throttle;

/* - * We maintain three lists of jobs: + * We maintain four lists of jobs: * * i) jobs waiting for pages * ii) jobs that have pages, and are waiting for the io to be issued. - * iii) jobs that have completed. + * iii) jobs that don't need to do any IO and just run a callback + * iv) jobs that have completed. * - * All three of these are protected by job_lock. + * All four of these are protected by job_lock. */ spinlock_t job_lock; + struct list_head callback_jobs; struct list_head complete_jobs; struct list_head io_jobs; struct list_head pages_jobs; @@ -584,6 +586,7 @@ static void do_work(struct work_struct *work) struct dm_kcopyd_client *kc = container_of(work, struct dm_kcopyd_client, kcopyd_work); struct blk_plug plug; + unsigned long flags;

/* * The order that these are called is *very* important. @@ -592,6 +595,10 @@ static void do_work(struct work_struct *work) * list. io jobs call wake when they complete and it all * starts again. */ + spin_lock_irqsave(&kc->job_lock, flags); + list_splice_tail_init(&kc->callback_jobs, &kc->complete_jobs); + spin_unlock_irqrestore(&kc->job_lock, flags); + blk_start_plug(&plug); process_jobs(&kc->complete_jobs, kc, run_complete_job); process_jobs(&kc->pages_jobs, kc, run_pages_job); @@ -609,7 +616,7 @@ static void dispatch_job(struct kcopyd_job *job) struct dm_kcopyd_client *kc = job->kc; atomic_inc(&kc->nr_jobs); if (unlikely(!job->source.count)) - push(&kc->complete_jobs, job); + push(&kc->callback_jobs, job); else if (job->pages == &zero_page_list) push(&kc->io_jobs, job); else @@ -796,7 +803,7 @@ void dm_kcopyd_do_callback(void *j, int read_err, unsigned long write_err) job->read_err = read_err; job->write_err = write_err;

- push(&kc->complete_jobs, job); + push(&kc->callback_jobs, job); wake(kc); } EXPORT_SYMBOL(dm_kcopyd_do_callback); @@ -826,6 +833,7 @@ struct dm_kcopyd_client *dm_kcopyd_client_create(struct dm_kcopyd_throttle *thro return ERR_PTR(-ENOMEM);

spin_lock_init(&kc->job_lock); + INIT_LIST_HEAD(&kc->callback_jobs); INIT_LIST_HEAD(&kc->complete_jobs); INIT_LIST_HEAD(&kc->io_jobs); INIT_LIST_HEAD(&kc->pages_jobs); @@ -875,6 +883,7 @@ void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc) /* Wait for completion of all jobs submitted by this client. */ wait_event(kc->destroyq, !atomic_read(&kc->nr_jobs));

+ BUG_ON(!list_empty(&kc->callback_jobs)); BUG_ON(!list_empty(&kc->complete_jobs)); BUG_ON(!list_empty(&kc->io_jobs)); BUG_ON(!list_empty(&kc->pages_jobs));

From: Nikos Tsironis ntsironis@arrikto.com

[ Upstream commit 721b1d98fb517ae99ab3b757021cf81db41e67be ]

kcopyd has no upper limit to the number of jobs one can allocate and issue. Under certain workloads this can lead to excessive memory usage and workqueue stalls. For example, when creating multiple dm-snapshot targets with a 4K chunk size and then writing to the origin through the page cache. Syncing the page cache causes a large number of BIOs to be issued to the dm-snapshot origin target, which itself issues an even larger (because of the BIO splitting taking place) number of kcopyd jobs.

Running the following test, from the device mapper test suite [1],

dmtest run --suite snapshot -n many_snapshots_of_same_volume_N

, with 8 active snapshots, results in the kcopyd job slab cache growing to 10G. Depending on the available system RAM this can lead to the OOM killer killing user processes:

[463.492878] kthreadd invoked oom-killer: gfp_mask=0x6040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null), order=1, oom_score_adj=0 [463.492894] kthreadd cpuset=/ mems_allowed=0 [463.492948] CPU: 7 PID: 2 Comm: kthreadd Not tainted 4.19.0-rc7 #3 [463.492950] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [463.492952] Call Trace: [463.492964] dump_stack+0x7d/0xbb [463.492973] dump_header+0x6b/0x2fc [463.492987] ? lockdep_hardirqs_on+0xee/0x190 [463.493012] oom_kill_process+0x302/0x370 [463.493021] out_of_memory+0x113/0x560 [463.493030] __alloc_pages_slowpath+0xf40/0x1020 [463.493055] __alloc_pages_nodemask+0x348/0x3c0 [463.493067] cache_grow_begin+0x81/0x8b0 [463.493072] ? cache_grow_begin+0x874/0x8b0 [463.493078] fallback_alloc+0x1e4/0x280 [463.493092] kmem_cache_alloc_node+0xd6/0x370 [463.493098] ? copy_process.part.31+0x1c5/0x20d0 [463.493105] copy_process.part.31+0x1c5/0x20d0 [463.493115] ? __lock_acquire+0x3cc/0x1550 [463.493121] ? __switch_to_asm+0x34/0x70 [463.493129] ? kthread_create_worker_on_cpu+0x70/0x70 [463.493135] ? finish_task_switch+0x90/0x280 [463.493165] _do_fork+0xe0/0x6d0 [463.493191] ? kthreadd+0x19f/0x220 [463.493233] kernel_thread+0x25/0x30 [463.493235] kthreadd+0x1bf/0x220 [463.493242] ? kthread_create_on_cpu+0x90/0x90 [463.493248] ret_from_fork+0x3a/0x50 [463.493279] Mem-Info: [463.493285] active_anon:20631 inactive_anon:4831 isolated_anon:0 [463.493285] active_file:80216 inactive_file:80107 isolated_file:435 [463.493285] unevictable:0 dirty:51266 writeback:109372 unstable:0 [463.493285] slab_reclaimable:31191 slab_unreclaimable:3483521 [463.493285] mapped:526 shmem:4903 pagetables:1759 bounce:0 [463.493285] free:33623 free_pcp:2392 free_cma:0 ... [463.493489] Unreclaimable slab info: [463.493513] Name Used Total [463.493522] bio-6 1028KB 1028KB [463.493525] bio-5 1028KB 1028KB [463.493528] dm_snap_pending_exception 236783KB 243789KB [463.493531] dm_exception 41KB 42KB [463.493534] bio-4 1216KB 1216KB [463.493537] bio-3 439396KB 439396KB [463.493539] kcopyd_job 6973427KB 6973427KB ... [463.494340] Out of memory: Kill process 1298 (ruby2.3) score 1 or sacrifice child [463.494673] Killed process 1298 (ruby2.3) total-vm:435740kB, anon-rss:20180kB, file-rss:4kB, shmem-rss:0kB [463.506437] oom_reaper: reaped process 1298 (ruby2.3), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB

Moreover, issuing a large number of kcopyd jobs results in kcopyd hogging the CPU, while processing them. As a result, processing of work items, queued for execution on the same CPU as the currently running kcopyd thread, is stalled for long periods of time, hurting performance. Running the aforementioned test we get, in dmesg, messages like the following:

[67501.194592] BUG: workqueue lockup - pool cpus=4 node=0 flags=0x0 nice=0 stuck for 27s! [67501.195586] Showing busy workqueues and worker pools: [67501.195591] workqueue events: flags=0x0 [67501.195597] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=1/256 [67501.195611] pending: cache_reap [67501.195641] workqueue mm_percpu_wq: flags=0x8 [67501.195645] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=1/256 [67501.195656] pending: vmstat_update [67501.195682] workqueue kblockd: flags=0x18 [67501.195687] pwq 5: cpus=2 node=0 flags=0x0 nice=-20 active=1/256 [67501.195698] pending: blk_timeout_work [67501.195753] workqueue kcopyd: flags=0x8 [67501.195757] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=1/256 [67501.195768] pending: do_work [dm_mod] [67501.195802] workqueue kcopyd: flags=0x8 [67501.195806] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=1/256 [67501.195817] pending: do_work [dm_mod] [67501.195834] workqueue kcopyd: flags=0x8 [67501.195838] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=1/256 [67501.195848] pending: do_work [dm_mod] [67501.195881] workqueue kcopyd: flags=0x8 [67501.195885] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=1/256 [67501.195896] pending: do_work [dm_mod] [67501.195920] workqueue kcopyd: flags=0x8 [67501.195924] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=2/256 [67501.195935] in-flight: 67:do_work [dm_mod] [67501.195945] pending: do_work [dm_mod] [67501.195961] pool 8: cpus=4 node=0 flags=0x0 nice=0 hung=27s workers=3 idle: 129 23765

The root cause for these issues is the way dm-snapshot uses kcopyd. In particular, the lack of an explicit or implicit limit to the maximum number of in-flight COW jobs. The merging path is not affected because it implicitly limits the in-flight kcopyd jobs to one.

Fix these issues by using a semaphore to limit the maximum number of in-flight kcopyd jobs. We grab the semaphore before allocating a new kcopyd job in start_copy() and start_full_bio() and release it after the job finishes in copy_callback().

The initial semaphore value is configurable through a module parameter, to allow fine tuning the maximum number of in-flight COW jobs. Setting this parameter to zero initializes the semaphore to INT_MAX.

A default value of 2048 maximum in-flight kcopyd jobs was chosen. This value was decided experimentally as a trade-off between memory consumption, stalling the kernel's workqueues and maintaining a high enough throughput.

Re-running the aforementioned test:

* Workqueue stalls are eliminated * kcopyd's job slab cache uses a maximum of 130MB * The time taken by the test to write to the snapshot-origin target is reduced from 05m20.48s to 03m26.38s

[1] https://github.com/jthornber/device-mapper-test-suite

Signed-off-by: Nikos Tsironis ntsironis@arrikto.com Signed-off-by: Ilias Tsitsimpis iliastsi@arrikto.com Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/dm-snap.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index c65feeada864..2da0b9b213c7 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -19,6 +19,7 @@ #include <linux/vmalloc.h> #include <linux/log2.h> #include <linux/dm-kcopyd.h> +#include <linux/semaphore.h>

#include "dm.h"

@@ -105,6 +106,9 @@ struct dm_snapshot { /* The on disk metadata handler */ struct dm_exception_store *store;

+ /* Maximum number of in-flight COW jobs. */ + struct semaphore cow_count; + struct dm_kcopyd_client *kcopyd_client;

/* Wait for events based on state_bits */ @@ -145,6 +149,19 @@ struct dm_snapshot { #define RUNNING_MERGE 0 #define SHUTDOWN_MERGE 1

+/* + * Maximum number of chunks being copied on write. + * + * The value was decided experimentally as a trade-off between memory + * consumption, stalling the kernel's workqueues and maintaining a high enough + * throughput. + */ +#define DEFAULT_COW_THRESHOLD 2048 + +static int cow_threshold = DEFAULT_COW_THRESHOLD; +module_param_named(snapshot_cow_threshold, cow_threshold, int, 0644); +MODULE_PARM_DESC(snapshot_cow_threshold, "Maximum number of chunks being copied on write"); + DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle, "A percentage of time allocated for copy on write");

@@ -1189,6 +1206,8 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) goto bad_hash_tables; }

+ sema_init(&s->cow_count, (cow_threshold > 0) ? cow_threshold : INT_MAX); + s->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle); if (IS_ERR(s->kcopyd_client)) { r = PTR_ERR(s->kcopyd_client); @@ -1560,6 +1579,7 @@ static void copy_callback(int read_err, unsigned long write_err, void *context) } list_add(&pe->out_of_order_entry, lh); } + up(&s->cow_count); }

/* @@ -1583,6 +1603,7 @@ static void start_copy(struct dm_snap_pending_exception *pe) dest.count = src.count;

/* Hand over to kcopyd */ + down(&s->cow_count); dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, copy_callback, pe); }

@@ -1602,6 +1623,7 @@ static void start_full_bio(struct dm_snap_pending_exception *pe, pe->full_bio = bio; pe->full_bio_end_io = bio->bi_end_io;

+ down(&s->cow_count); callback_data = dm_kcopyd_prepare_callback(s->kcopyd_client, copy_callback, pe);

From: Daniel Vetter daniel.vetter@ffwll.ch

[ Upstream commit 4f4b374332ec0ae9c738ff8ec9bed5cd97ff9adc ]

This is the much more correct fix for my earlier attempt at:

https://lkml.org/lkml/2018/12/10/118

Short recap:

- There's not actually a locking issue, it's just lockdep being a bit too eager to complain about a possible deadlock.

- Contrary to what I claimed the real problem is recursion on kn->count. Greg pointed me at sysfs_break_active_protection(), used by the scsi subsystem to allow a sysfs file to unbind itself. That would be a real deadlock, which isn't what's happening here. Also, breaking the active protection means we'd need to manually handle all the lifetime fun.

- With Rafael we discussed the task_work approach, which kinda works, but has two downsides: It's a functional change for a lockdep annotation issue, and it won't work for the bind file (which needs to get the errno from the driver load function back to userspace).

- Greg also asked why this never showed up: To hit this you need to unregister a 2nd driver from the unload code of your first driver. I guess only gpus do that. The bug has always been there, but only with a recent patch series did we add more locks so that lockdep built a chain from unbinding the snd-hda driver to the acpi_video_unregister call.

Full lockdep splat:

[12301.898799] ============================================ [12301.898805] WARNING: possible recursive locking detected [12301.898811] 4.20.0-rc7+ #84 Not tainted [12301.898815] -------------------------------------------- [12301.898821] bash/5297 is trying to acquire lock: [12301.898826] 00000000f61c6093 (kn->count#39){++++}, at: kernfs_remove_by_name_ns+0x3b/0x80 [12301.898841] but task is already holding lock: [12301.898847] 000000005f634021 (kn->count#39){++++}, at: kernfs_fop_write+0xdc/0x190 [12301.898856] other info that might help us debug this: [12301.898862] Possible unsafe locking scenario: [12301.898867] CPU0 [12301.898870] ---- [12301.898874] lock(kn->count#39); [12301.898879] lock(kn->count#39); [12301.898883] *** DEADLOCK *** [12301.898891] May be due to missing lock nesting notation [12301.898899] 5 locks held by bash/5297: [12301.898903] #0: 00000000cd800e54 (sb_writers#4){.+.+}, at: vfs_write+0x17f/0x1b0 [12301.898915] #1: 000000000465e7c2 (&of->mutex){+.+.}, at: kernfs_fop_write+0xd3/0x190 [12301.898925] #2: 000000005f634021 (kn->count#39){++++}, at: kernfs_fop_write+0xdc/0x190 [12301.898936] #3: 00000000414ef7ac (&dev->mutex){....}, at: device_release_driver_internal+0x34/0x240 [12301.898950] #4: 000000003218fbdf (register_count_mutex){+.+.}, at: acpi_video_unregister+0xe/0x40 [12301.898960] stack backtrace: [12301.898968] CPU: 1 PID: 5297 Comm: bash Not tainted 4.20.0-rc7+ #84 [12301.898974] Hardware name: Hewlett-Packard HP EliteBook 8460p/161C, BIOS 68SCF Ver. F.01 03/11/2011 [12301.898982] Call Trace: [12301.898989] dump_stack+0x67/0x9b [12301.898997] __lock_acquire+0x6ad/0x1410 [12301.899003] ? kernfs_remove_by_name_ns+0x3b/0x80 [12301.899010] ? find_held_lock+0x2d/0x90 [12301.899017] ? mutex_spin_on_owner+0xe4/0x150 [12301.899023] ? find_held_lock+0x2d/0x90 [12301.899030] ? lock_acquire+0x90/0x180 [12301.899036] lock_acquire+0x90/0x180 [12301.899042] ? kernfs_remove_by_name_ns+0x3b/0x80 [12301.899049] __kernfs_remove+0x296/0x310 [12301.899055] ? kernfs_remove_by_name_ns+0x3b/0x80 [12301.899060] ? kernfs_name_hash+0xd/0x80 [12301.899066] ? kernfs_find_ns+0x6c/0x100 [12301.899073] kernfs_remove_by_name_ns+0x3b/0x80 [12301.899080] bus_remove_driver+0x92/0xa0 [12301.899085] acpi_video_unregister+0x24/0x40 [12301.899127] i915_driver_unload+0x42/0x130 [i915] [12301.899160] i915_pci_remove+0x19/0x30 [i915] [12301.899169] pci_device_remove+0x36/0xb0 [12301.899176] device_release_driver_internal+0x185/0x240 [12301.899183] unbind_store+0xaf/0x180 [12301.899189] kernfs_fop_write+0x104/0x190 [12301.899195] __vfs_write+0x31/0x180 [12301.899203] ? rcu_read_lock_sched_held+0x6f/0x80 [12301.899209] ? rcu_sync_lockdep_assert+0x29/0x50 [12301.899216] ? __sb_start_write+0x13c/0x1a0 [12301.899221] ? vfs_write+0x17f/0x1b0 [12301.899227] vfs_write+0xb9/0x1b0 [12301.899233] ksys_write+0x50/0xc0 [12301.899239] do_syscall_64+0x4b/0x180 [12301.899247] entry_SYSCALL_64_after_hwframe+0x49/0xbe [12301.899253] RIP: 0033:0x7f452ac7f7a4 [12301.899259] Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 80 00 00 00 00 8b 05 aa f0 2c 00 48 63 ff 85 c0 75 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 f3 c3 66 90 55 53 48 89 d5 48 89 f3 48 83 [12301.899273] RSP: 002b:00007ffceafa6918 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [12301.899282] RAX: ffffffffffffffda RBX: 000000000000000d RCX: 00007f452ac7f7a4 [12301.899288] RDX: 000000000000000d RSI: 00005612a1abf7c0 RDI: 0000000000000001 [12301.899295] RBP: 00005612a1abf7c0 R08: 000000000000000a R09: 00005612a1c46730 [12301.899301] R10: 000000000000000a R11: 0000000000000246 R12: 000000000000000d [12301.899308] R13: 0000000000000001 R14: 00007f452af4a740 R15: 000000000000000d

Looking around I've noticed that usb and i2c already handle similar recursion problems, where a sysfs file can unbind the same type of sysfs somewhere else in the hierarchy. Relevant commits are:

commit 356c05d58af05d582e634b54b40050c73609617b Author: Alan Stern stern@rowland.harvard.edu Date: Mon May 14 13:30:03 2012 -0400

sysfs: get rid of some lockdep false positives

commit e9b526fe704812364bca07edd15eadeba163ebfb Author: Alexander Sverdlin alexander.sverdlin@nsn.com Date: Fri May 17 14:56:35 2013 +0200

i2c: suppress lockdep warning on delete_device

Implement the same trick for driver bind/unbind.

v2: Put the macro into bus.c (Greg).

Reviewed-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Cc: Ramalingam C ramalingam.c@intel.com Cc: Arend van Spriel aspriel@gmail.com Cc: Andy Shevchenko andriy.shevchenko@linux.intel.com Cc: Geert Uytterhoeven geert+renesas@glider.be Cc: Bartosz Golaszewski brgl@bgdev.pl Cc: Heikki Krogerus heikki.krogerus@linux.intel.com Cc: Vivek Gautam vivek.gautam@codeaurora.org Cc: Joe Perches joe@perches.com Signed-off-by: Daniel Vetter daniel.vetter@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/base/bus.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c index e32a74eb28a3..a7ae9a0e8a78 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -33,6 +33,9 @@ static struct kset *system_kset;

#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)

+#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \ + struct driver_attribute driver_attr_##_name = \ + __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)

static int __must_check bus_rescan_devices_helper(struct device *dev, void *data); @@ -197,7 +200,7 @@ static ssize_t unbind_store(struct device_driver *drv, const char *buf, bus_put(bus); return err; } -static DRIVER_ATTR_WO(unbind); +static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, S_IWUSR, NULL, unbind_store);

/* * Manually attach a device to a driver. @@ -233,7 +236,7 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf, bus_put(bus); return err; } -static DRIVER_ATTR_WO(bind); +static DRIVER_ATTR_IGNORE_LOCKDEP(bind, S_IWUSR, NULL, bind_store);

static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf) {

From: Qian Cai cai@lca.pw

[ Upstream commit c7a082e4242fd8cd21a441071e622f87c16bdacc ]

UBSAN reported those with MegaRAID SAS-3 3108,

[ 77.467308] UBSAN: Undefined behaviour in drivers/scsi/megaraid/megaraid_sas_fp.c:117:32 [ 77.475402] index 255 is out of range for type 'MR_LD_SPAN_MAP [1]' [ 77.481677] CPU: 16 PID: 333 Comm: kworker/16:1 Not tainted 4.20.0-rc5+ #1 [ 77.488556] Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.50 06/01/2018 [ 77.495791] Workqueue: events work_for_cpu_fn [ 77.500154] Call trace: [ 77.502610] dump_backtrace+0x0/0x2c8 [ 77.506279] show_stack+0x24/0x30 [ 77.509604] dump_stack+0x118/0x19c [ 77.513098] ubsan_epilogue+0x14/0x60 [ 77.516765] __ubsan_handle_out_of_bounds+0xfc/0x13c [ 77.521767] mr_update_load_balance_params+0x150/0x158 [megaraid_sas] [ 77.528230] MR_ValidateMapInfo+0x2cc/0x10d0 [megaraid_sas] [ 77.533825] megasas_get_map_info+0x244/0x2f0 [megaraid_sas] [ 77.539505] megasas_init_adapter_fusion+0x9b0/0xf48 [megaraid_sas] [ 77.545794] megasas_init_fw+0x1ab4/0x3518 [megaraid_sas] [ 77.551212] megasas_probe_one+0x2c4/0xbe0 [megaraid_sas] [ 77.556614] local_pci_probe+0x7c/0xf0 [ 77.560365] work_for_cpu_fn+0x34/0x50 [ 77.564118] process_one_work+0x61c/0xf08 [ 77.568129] worker_thread+0x534/0xa70 [ 77.571882] kthread+0x1c8/0x1d0 [ 77.575114] ret_from_fork+0x10/0x1c

[ 89.240332] UBSAN: Undefined behaviour in drivers/scsi/megaraid/megaraid_sas_fp.c:117:32 [ 89.248426] index 255 is out of range for type 'MR_LD_SPAN_MAP [1]' [ 89.254700] CPU: 16 PID: 95 Comm: kworker/u130:0 Not tainted 4.20.0-rc5+ #1 [ 89.261665] Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.50 06/01/2018 [ 89.268903] Workqueue: events_unbound async_run_entry_fn [ 89.274222] Call trace: [ 89.276680] dump_backtrace+0x0/0x2c8 [ 89.280348] show_stack+0x24/0x30 [ 89.283671] dump_stack+0x118/0x19c [ 89.287167] ubsan_epilogue+0x14/0x60 [ 89.290835] __ubsan_handle_out_of_bounds+0xfc/0x13c [ 89.295828] MR_LdRaidGet+0x50/0x58 [megaraid_sas] [ 89.300638] megasas_build_io_fusion+0xbb8/0xd90 [megaraid_sas] [ 89.306576] megasas_build_and_issue_cmd_fusion+0x138/0x460 [megaraid_sas] [ 89.313468] megasas_queue_command+0x398/0x3d0 [megaraid_sas] [ 89.319222] scsi_dispatch_cmd+0x1dc/0x8a8 [ 89.323321] scsi_request_fn+0x8e8/0xdd0 [ 89.327249] __blk_run_queue+0xc4/0x158 [ 89.331090] blk_execute_rq_nowait+0xf4/0x158 [ 89.335449] blk_execute_rq+0xdc/0x158 [ 89.339202] __scsi_execute+0x130/0x258 [ 89.343041] scsi_probe_and_add_lun+0x2fc/0x1488 [ 89.347661] __scsi_scan_target+0x1cc/0x8c8 [ 89.351848] scsi_scan_channel.part.3+0x8c/0xc0 [ 89.356382] scsi_scan_host_selected+0x130/0x1f0 [ 89.361002] do_scsi_scan_host+0xd8/0xf0 [ 89.364927] do_scan_async+0x9c/0x320 [ 89.368594] async_run_entry_fn+0x138/0x420 [ 89.372780] process_one_work+0x61c/0xf08 [ 89.376793] worker_thread+0x13c/0xa70 [ 89.380546] kthread+0x1c8/0x1d0 [ 89.383778] ret_from_fork+0x10/0x1c

This is because when populating Driver Map using firmware raid map, all non-existing VDs set their ldTgtIdToLd to 0xff, so it can be skipped later.

From drivers/scsi/megaraid/megaraid_sas_base.c ,

memset(instance->ld_ids, 0xff, MEGASAS_MAX_LD_IDS);

From drivers/scsi/megaraid/megaraid_sas_fp.c ,

/* For non existing VDs, iterate to next VD*/ if (ld >= (MAX_LOGICAL_DRIVES_EXT - 1)) continue;

However, there are a few places that failed to skip those non-existing VDs due to off-by-one errors. Then, those 0xff leaked into MR_LdRaidGet(0xff, map) and triggered the out-of-bound accesses.

Fixes: 51087a8617fe ("megaraid_sas : Extended VD support") Signed-off-by: Qian Cai cai@lca.pw Acked-by: Sumit Saxena sumit.saxena@broadcom.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/megaraid/megaraid_sas_fp.c | 2 +- drivers/scsi/megaraid/megaraid_sas_fusion.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_fp.c b/drivers/scsi/megaraid/megaraid_sas_fp.c index e413113c86ac..663d8f503c86 100644 --- a/drivers/scsi/megaraid/megaraid_sas_fp.c +++ b/drivers/scsi/megaraid/megaraid_sas_fp.c @@ -1275,7 +1275,7 @@ void mr_update_load_balance_params(struct MR_DRV_RAID_MAP_ALL *drv_map,

for (ldCount = 0; ldCount < MAX_LOGICAL_DRIVES_EXT; ldCount++) { ld = MR_TargetIdToLdGet(ldCount, drv_map); - if (ld >= MAX_LOGICAL_DRIVES_EXT) { + if (ld >= MAX_LOGICAL_DRIVES_EXT - 1) { lbInfo[ldCount].loadBalanceFlag = 0; continue; } diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c index f722a0e6caa4..fe1a20973e47 100644 --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c @@ -1902,7 +1902,7 @@ static void megasas_build_ld_nonrw_fusion(struct megasas_instance *instance, device_id < instance->fw_supported_vd_count)) {

ld = MR_TargetIdToLdGet(device_id, local_map_ptr); - if (ld >= instance->fw_supported_vd_count) + if (ld >= instance->fw_supported_vd_count - 1) fp_possible = 0;

raid = MR_LdRaidGet(ld, local_map_ptr);

From: Brian Foster bfoster@redhat.com

[ Upstream commit 3fa750dcf29e8606e3969d13d8e188cc1c0f511d ]

write_cache_pages() is used in both background and integrity writeback scenarios by various filesystems. Background writeback is mostly concerned with cleaning a certain number of dirty pages based on various mm heuristics. It may not write the full set of dirty pages or wait for I/O to complete. Integrity writeback is responsible for persisting a set of dirty pages before the writeback job completes. For example, an fsync() call must perform integrity writeback to ensure data is on disk before the call returns.

write_cache_pages() unconditionally breaks out of its processing loop in the event of a ->writepage() error. This is fine for background writeback, which had no strict requirements and will eventually come around again. This can cause problems for integrity writeback on filesystems that might need to clean up state associated with failed page writeouts. For example, XFS performs internal delayed allocation accounting before returning a ->writepage() error, where applicable. If the current writeback happens to be associated with an unmount and write_cache_pages() completes the writeback prematurely due to error, the filesystem is unmounted in an inconsistent state if dirty+delalloc pages still exist.

To handle this problem, update write_cache_pages() to always process the full set of pages for integrity writeback regardless of ->writepage() errors. Save the first encountered error and return it to the caller once complete. This facilitates XFS (or any other fs that expects integrity writeback to process the entire set of dirty pages) to clean up its internal state completely in the event of persistent mapping errors. Background writeback continues to exit on the first error encountered.

[akpm@linux-foundation.org: fix typo in comment] Link: http://lkml.kernel.org/r/20181116134304.32440-1-bfoster@redhat.com Signed-off-by: Brian Foster bfoster@redhat.com Reviewed-by: Jan Kara jack@suse.cz Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- mm/page-writeback.c | 35 +++++++++++++++++++++-------------- 1 file changed, 21 insertions(+), 14 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 807236aed275..281a46aeae61 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2148,6 +2148,7 @@ int write_cache_pages(struct address_space *mapping, { int ret = 0; int done = 0; + int error; struct pagevec pvec; int nr_pages; pgoff_t uninitialized_var(writeback_index); @@ -2244,25 +2245,31 @@ int write_cache_pages(struct address_space *mapping, goto continue_unlock;

trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); - ret = (*writepage)(page, wbc, data); - if (unlikely(ret)) { - if (ret == AOP_WRITEPAGE_ACTIVATE) { + error = (*writepage)(page, wbc, data); + if (unlikely(error)) { + /* + * Handle errors according to the type of + * writeback. There's no need to continue for + * background writeback. Just push done_index + * past this page so media errors won't choke + * writeout for the entire file. For integrity + * writeback, we must process the entire dirty + * set regardless of errors because the fs may + * still have state to clear for each page. In + * that case we continue processing and return + * the first error. + */ + if (error == AOP_WRITEPAGE_ACTIVATE) { unlock_page(page); - ret = 0; - } else { - /* - * done_index is set past this page, - * so media errors will not choke - * background writeout for the entire - * file. This has consequences for - * range_cyclic semantics (ie. it may - * not be suitable for data integrity - * writeout). - */ + error = 0; + } else if (wbc->sync_mode != WB_SYNC_ALL) { + ret = error; done_index = page->index + 1; done = 1; break; } + if (!ret) + ret = error; }

/*