[PATCH AUTOSEL 6.1 01/12] cpu/hotplug: Reset task stack state in _cpu_up()

[PATCH AUTOSEL 6.1 01/12] cpu/hotplug: Reset task stack state in _cpu_up()

[Sasha Levin]

From: David Woodhouse <dwmw@amazon.co.uk>

[ Upstream commit 6d712b9b3a58018259fb40ddd498d1f7dfa1f4ec ]

Commit dce1ca0525bf ("sched/scs: Reset task stack state in bringup_cpu()")
ensured that the shadow call stack and KASAN poisoning were removed from
a CPU's stack each time that CPU is brought up, not just once.

This is not incorrect. However, with parallel bringup the idle thread setup
will happen at a different step. As a consequence the cleanup in
bringup_cpu() would be too late.

Move the SCS/KASAN cleanup to the generic _cpu_up() function instead,
which already ensures that the new CPU's stack is available, purely to
allow for early failure. This occurs when the CPU to be brought up is
in the CPUHP_OFFLINE state, which should correctly do the cleanup any
time the CPU has been taken down to the point where such is needed.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Link: https://lore.kernel.org/r/20230512205257.027075560@linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/cpu.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 98a7a7b1471b7..dbf1e572f6e7d 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -591,12 +591,6 @@ static int bringup_cpu(unsigned int cpu)
 	struct task_struct *idle = idle_thread_get(cpu);
 	int ret;
 
-	/*
-	 * Reset stale stack state from the last time this CPU was online.
-	 */
-	scs_task_reset(idle);
-	kasan_unpoison_task_stack(idle);
-
 	/*
 	 * Some architectures have to walk the irq descriptors to
 	 * setup the vector space for the cpu which comes online.
@@ -1383,6 +1377,12 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
 			ret = PTR_ERR(idle);
 			goto out;
 		}
+
+		/*
+		 * Reset stale stack state from the last time this CPU was online.
+		 */
+		scs_task_reset(idle);
+		kasan_unpoison_task_stack(idle);
 	}
 
 	cpuhp_tasks_frozen = tasks_frozen;
-- 
2.39.2

[PATCH AUTOSEL 6.1 02/12] io_uring: annotate offset timeout races

[Sasha Levin]

From: Pavel Begunkov <asml.silence@gmail.com>

[ Upstream commit 5498bf28d8f2bd63a46ad40f4427518615fb793f ]

It's racy to read ->cached_cq_tail without taking proper measures
(usually grabbing ->completion_lock) as timeout requests with CQE
offsets do, however they have never had a good semantics for from
when they start counting. Annotate racy reads with data_race().

Reported-by: syzbot+cb265db2f3f3468ef436@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4de3685e185832a92a572df2be2c735d2e21a83d.1684506056.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 io_uring/timeout.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/io_uring/timeout.c b/io_uring/timeout.c
index 4c6a5666541cf..b0cf05ebcbcc3 100644
--- a/io_uring/timeout.c
+++ b/io_uring/timeout.c
@@ -545,7 +545,7 @@ int io_timeout(struct io_kiocb *req, unsigned int issue_flags)
 		goto add;
 	}
 
-	tail = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts);
+	tail = data_race(ctx->cached_cq_tail) - atomic_read(&ctx->cq_timeouts);
 	timeout->target_seq = tail + off;
 
 	/* Update the last seq here in case io_flush_timeouts() hasn't.
-- 
2.39.2

[PATCH AUTOSEL 6.1 03/12] x86/amd_nb: Add MI200 PCI IDs

[Sasha Levin]

From: Yazen Ghannam <yazen.ghannam@amd.com>

[ Upstream commit e15885689cf4bc92356e52ea6ef38379a749819a ]

The AMD MI200 series accelerators are data center GPUs. They include
unified memory controllers and a data fabric similar to those used in
AMD x86 CPU products. The memory controllers report errors using MCA,
though these errors are generally handled through GPU drivers that
directly manage the accelerator device.

In some configurations, memory errors from these devices will be
reported through MCA and managed by x86 CPUs. The OS is expected to
handle these errors in similar fashion to MCA errors originating from
memory controllers on the CPUs. In Linux, this flow includes passing MCA
errors to a notifier chain with handlers in the EDAC subsystem.

The AMD64 EDAC module requires information from the memory controllers
and data fabric in order to provide detailed decoding of memory errors.
The information is read from hardware registers accessed through
interfaces in the data fabric.

The accelerator data fabrics are visible to the host x86 CPUs as PCI
devices just like x86 CPU data fabrics are already. However, the
accelerator fabrics have new and unique PCI IDs.

Add PCI IDs for the MI200 series of accelerator devices in order to
enable EDAC support. The data fabrics of the accelerator devices will be
enumerated as any other fabric already supported.  System-specific
implementation details will be handled within the AMD64 EDAC module.

  [ bp: Scrub off marketing speak. ]

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Co-developed-by: Muralidhara M K <muralidhara.mk@amd.com>
Signed-off-by: Muralidhara M K <muralidhara.mk@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230515113537.1052146-2-muralimk@amd.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kernel/amd_nb.c | 5 +++++
 include/linux/pci_ids.h  | 1 +
 2 files changed, 6 insertions(+)

diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
index 7e331e8f36929..8fd955414b089 100644
--- a/arch/x86/kernel/amd_nb.c
+++ b/arch/x86/kernel/amd_nb.c
@@ -23,6 +23,7 @@
 #define PCI_DEVICE_ID_AMD_19H_M10H_ROOT	0x14a4
 #define PCI_DEVICE_ID_AMD_19H_M60H_ROOT	0x14d8
 #define PCI_DEVICE_ID_AMD_19H_M70H_ROOT	0x14e8
+#define PCI_DEVICE_ID_AMD_MI200_ROOT	0x14bb
 #define PCI_DEVICE_ID_AMD_17H_DF_F4	0x1464
 #define PCI_DEVICE_ID_AMD_17H_M10H_DF_F4 0x15ec
 #define PCI_DEVICE_ID_AMD_17H_M30H_DF_F4 0x1494
@@ -37,6 +38,7 @@
 #define PCI_DEVICE_ID_AMD_19H_M60H_DF_F4 0x14e4
 #define PCI_DEVICE_ID_AMD_19H_M70H_DF_F4 0x14f4
 #define PCI_DEVICE_ID_AMD_19H_M78H_DF_F4 0x12fc
+#define PCI_DEVICE_ID_AMD_MI200_DF_F4	0x14d4
 
 /* Protect the PCI config register pairs used for SMN. */
 static DEFINE_MUTEX(smn_mutex);
@@ -53,6 +55,7 @@ static const struct pci_device_id amd_root_ids[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M40H_ROOT) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M60H_ROOT) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M70H_ROOT) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_MI200_ROOT) },
 	{}
 };
 
@@ -81,6 +84,7 @@ static const struct pci_device_id amd_nb_misc_ids[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M60H_DF_F3) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M70H_DF_F3) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M78H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_MI200_DF_F3) },
 	{}
 };
 
@@ -101,6 +105,7 @@ static const struct pci_device_id amd_nb_link_ids[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M40H_DF_F4) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M50H_DF_F4) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CNB17H_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_MI200_DF_F4) },
 	{}
 };
 
diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
index 95f33dadb2be2..a99b1fcfc6174 100644
--- a/include/linux/pci_ids.h
+++ b/include/linux/pci_ids.h
@@ -568,6 +568,7 @@
 #define PCI_DEVICE_ID_AMD_19H_M60H_DF_F3 0x14e3
 #define PCI_DEVICE_ID_AMD_19H_M70H_DF_F3 0x14f3
 #define PCI_DEVICE_ID_AMD_19H_M78H_DF_F3 0x12fb
+#define PCI_DEVICE_ID_AMD_MI200_DF_F3	0x14d3
 #define PCI_DEVICE_ID_AMD_CNB17H_F3	0x1703
 #define PCI_DEVICE_ID_AMD_LANCE		0x2000
 #define PCI_DEVICE_ID_AMD_LANCE_HOME	0x2001
-- 
2.39.2

[PATCH AUTOSEL 6.1 04/12] debugobjects: Recheck debug_objects_enabled before reporting

[Sasha Levin]

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

[ Upstream commit 8b64d420fe2450f82848178506d3e3a0bd195539 ]

syzbot is reporting false a positive ODEBUG message immediately after
ODEBUG was disabled due to OOM.

  [ 1062.309646][T22911] ODEBUG: Out of memory. ODEBUG disabled
  [ 1062.886755][ T5171] ------------[ cut here ]------------
  [ 1062.892770][ T5171] ODEBUG: assert_init not available (active state 0) object: ffffc900056afb20 object type: timer_list hint: process_timeout+0x0/0x40

  CPU 0 [ T5171]                CPU 1 [T22911]
  --------------                --------------
  debug_object_assert_init() {
    if (!debug_objects_enabled)
      return;
    db = get_bucket(addr);
                                lookup_object_or_alloc() {
                                  debug_objects_enabled = 0;
                                  return NULL;
                                }
                                debug_objects_oom() {
                                  pr_warn("Out of memory. ODEBUG disabled\n");
                                  // all buckets get emptied here, and
                                }
    lookup_object_or_alloc(addr, db, descr, false, true) {
      // this bucket is already empty.
      return ERR_PTR(-ENOENT);
    }
    // Emits false positive warning.
    debug_print_object(&o, "assert_init");
  }

Recheck debug_object_enabled in debug_print_object() to avoid that.

Reported-by: syzbot <syzbot+7937ba6a50bdd00fffdf@syzkaller.appspotmail.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/492fe2ae-5141-d548-ebd5-62f5fe2e57f7@I-love.SAKURA.ne.jp
Closes: https://syzkaller.appspot.com/bug?extid=7937ba6a50bdd00fffdf
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 lib/debugobjects.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index c46736210363a..dacb80c22c4f1 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -498,6 +498,15 @@ static void debug_print_object(struct debug_obj *obj, char *msg)
 	const struct debug_obj_descr *descr = obj->descr;
 	static int limit;
 
+	/*
+	 * Don't report if lookup_object_or_alloc() by the current thread
+	 * failed because lookup_object_or_alloc()/debug_objects_oom() by a
+	 * concurrent thread turned off debug_objects_enabled and cleared
+	 * the hash buckets.
+	 */
+	if (!debug_objects_enabled)
+		return;
+
 	if (limit < 5 && descr != descr_test) {
 		void *hint = descr->debug_hint ?
 			descr->debug_hint(obj->object) : NULL;
-- 
2.39.2

[PATCH AUTOSEL 6.1 05/12] nbd: Add the maximum limit of allocated index in nbd_dev_add

[Sasha Levin]

From: Zhong Jinghua <zhongjinghua@huawei.com>

[ Upstream commit f12bc113ce904777fd6ca003b473b427782b3dde ]

If the index allocated by idr_alloc greater than MINORMASK >> part_shift,
the device number will overflow, resulting in failure to create a block
device.

Fix it by imiting the size of the max allocation.

Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230605122159.2134384-1-zhongjinghua@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/nbd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 7718c81e1dba8..8d75faa25076d 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1775,7 +1775,8 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
 		if (err == -ENOSPC)
 			err = -EEXIST;
 	} else {
-		err = idr_alloc(&nbd_index_idr, nbd, 0, 0, GFP_KERNEL);
+		err = idr_alloc(&nbd_index_idr, nbd, 0,
+				(MINORMASK >> part_shift) + 1, GFP_KERNEL);
 		if (err >= 0)
 			index = err;
 	}
-- 
2.39.2

[PATCH AUTOSEL 6.1 06/12] md: fix data corruption for raid456 when reshape restart while grow up

[Sasha Levin]

From: Yu Kuai <yukuai3@huawei.com>

[ Upstream commit 873f50ece41aad5c4f788a340960c53774b5526e ]

Currently, if reshape is interrupted, echo "reshape" to sync_action will
restart reshape from scratch, for example:

echo frozen > sync_action
echo reshape > sync_action

This will corrupt data before reshape_position if the array is growing,
fix the problem by continue reshape from reshape_position.

Reported-by: Peter Neuwirth <reddunur@online.de>
Link: https://lore.kernel.org/linux-raid/e2f96772-bfbc-f43b-6da1-f520e5164536@online.de/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230512015610.821290-3-yukuai1@huaweicloud.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/md.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index bb73a541bb193..a5b38fc3e65c9 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4839,11 +4839,21 @@ action_store(struct mddev *mddev, const char *page, size_t len)
 			return -EINVAL;
 		err = mddev_lock(mddev);
 		if (!err) {
-			if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+			if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
 				err =  -EBUSY;
-			else {
+			} else if (mddev->reshape_position == MaxSector ||
+				   mddev->pers->check_reshape == NULL ||
+				   mddev->pers->check_reshape(mddev)) {
 				clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 				err = mddev->pers->start_reshape(mddev);
+			} else {
+				/*
+				 * If reshape is still in progress, and
+				 * md_check_recovery() can continue to reshape,
+				 * don't restart reshape because data can be
+				 * corrupted for raid456.
+				 */
+				clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 			}
 			mddev_unlock(mddev);
 		}
-- 
2.39.2

[PATCH AUTOSEL 6.1 07/12] md/raid10: prevent soft lockup while flush writes

[Sasha Levin]

From: Yu Kuai <yukuai3@huawei.com>

[ Upstream commit 010444623e7f4da6b4a4dd603a7da7469981e293 ]

Currently, there is no limit for raid1/raid10 plugged bio. While flushing
writes, raid1 has cond_resched() while raid10 doesn't, and too many
writes can cause soft lockup.

Follow up soft lockup can be triggered easily with writeback test for
raid10 with ramdisks:

watchdog: BUG: soft lockup - CPU#10 stuck for 27s! [md0_raid10:1293]
Call Trace:
 <TASK>
 call_rcu+0x16/0x20
 put_object+0x41/0x80
 __delete_object+0x50/0x90
 delete_object_full+0x2b/0x40
 kmemleak_free+0x46/0xa0
 slab_free_freelist_hook.constprop.0+0xed/0x1a0
 kmem_cache_free+0xfd/0x300
 mempool_free_slab+0x1f/0x30
 mempool_free+0x3a/0x100
 bio_free+0x59/0x80
 bio_put+0xcf/0x2c0
 free_r10bio+0xbf/0xf0
 raid_end_bio_io+0x78/0xb0
 one_write_done+0x8a/0xa0
 raid10_end_write_request+0x1b4/0x430
 bio_endio+0x175/0x320
 brd_submit_bio+0x3b9/0x9b7 [brd]
 __submit_bio+0x69/0xe0
 submit_bio_noacct_nocheck+0x1e6/0x5a0
 submit_bio_noacct+0x38c/0x7e0
 flush_pending_writes+0xf0/0x240
 raid10d+0xac/0x1ed0

Fix the problem by adding cond_resched() to raid10 like what raid1 did.

Note that unlimited plugged bio still need to be optimized, for example,
in the case of lots of dirty pages writeback, this will take lots of
memory and io will spend a long time in plug, hence io latency is bad.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230529131106.2123367-2-yukuai1@huaweicloud.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/raid10.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 67398394cc9c9..dfe69420c0fbc 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -921,6 +921,7 @@ static void flush_pending_writes(struct r10conf *conf)
 			else
 				submit_bio_noacct(bio);
 			bio = next;
+			cond_resched();
 		}
 		blk_finish_plug(&plug);
 	} else
@@ -1140,6 +1141,7 @@ static void raid10_unplug(struct blk_plug_cb *cb, bool from_schedule)
 		else
 			submit_bio_noacct(bio);
 		bio = next;
+		cond_resched();
 	}
 	kfree(plug);
 }
-- 
2.39.2

[PATCH AUTOSEL 6.1 08/12] scsi: sg: fix blktrace debugfs entries leakage

[Sasha Levin]

From: Yu Kuai <yukuai3@huawei.com>

[ Upstream commit db59133e927916d8a25ee1fd8264f2808040909d ]

sg_ioctl() support to enable blktrace, which will create debugfs entries
"/sys/kernel/debug/block/sgx/", however, there is no guarantee that user
will remove these entries through ioctl, and deleting sg device doesn't
cleanup these blktrace entries.

This problem can be fixed by cleanup blktrace while releasing
request_queue, however, it's not a good idea to do this special handling
in common layer just for sg device.

Fix this problem by shutdown bltkrace in sg_device_destroy(), where the
device is deleted and all the users close the device, also grab a
scsi_device reference from sg_add_device() to prevent scsi_device to be
freed before sg_device_destroy();

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20230610022003.2557284-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/scsi/sg.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 12344be14232b..3d7c27f0bd688 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1496,6 +1496,10 @@ sg_add_device(struct device *cl_dev, struct class_interface *cl_intf)
 	int error;
 	unsigned long iflags;
 
+	error = scsi_device_get(scsidp);
+	if (error)
+		return error;
+
 	error = -ENOMEM;
 	cdev = cdev_alloc();
 	if (!cdev) {
@@ -1553,6 +1557,7 @@ sg_add_device(struct device *cl_dev, struct class_interface *cl_intf)
 out:
 	if (cdev)
 		cdev_del(cdev);
+	scsi_device_put(scsidp);
 	return error;
 }
 
@@ -1560,6 +1565,7 @@ static void
 sg_device_destroy(struct kref *kref)
 {
 	struct sg_device *sdp = container_of(kref, struct sg_device, d_ref);
+	struct request_queue *q = sdp->device->request_queue;
 	unsigned long flags;
 
 	/* CAUTION!  Note that the device can still be found via idr_find()
@@ -1567,6 +1573,9 @@ sg_device_destroy(struct kref *kref)
 	 * any other cleanup.
 	 */
 
+	blk_trace_remove(q);
+	scsi_device_put(sdp->device);
+
 	write_lock_irqsave(&sg_index_lock, flags);
 	idr_remove(&sg_index_idr, sdp->index);
 	write_unlock_irqrestore(&sg_index_lock, flags);
-- 
2.39.2

[PATCH AUTOSEL 6.1 09/12] posix-timers: Ensure timer ID search-loop limit is valid

[Sasha Levin]

From: Thomas Gleixner <tglx@linutronix.de>

[ Upstream commit 8ce8849dd1e78dadcee0ec9acbd259d239b7069f ]

posix_timer_add() tries to allocate a posix timer ID by starting from the
cached ID which was stored by the last successful allocation.

This is done in a loop searching the ID space for a free slot one by
one. The loop has to terminate when the search wrapped around to the
starting point.

But that's racy vs. establishing the starting point. That is read out
lockless, which leads to the following problem:

CPU0	  	      	     	   CPU1
posix_timer_add()
  start = sig->posix_timer_id;
  lock(hash_lock);
  ...				   posix_timer_add()
  if (++sig->posix_timer_id < 0)
      			             start = sig->posix_timer_id;
     sig->posix_timer_id = 0;

So CPU1 can observe a negative start value, i.e. -1, and the loop break
never happens because the condition can never be true:

  if (sig->posix_timer_id == start)
     break;

While this is unlikely to ever turn into an endless loop as the ID space is
huge (INT_MAX), the racy read of the start value caught the attention of
KCSAN and Dmitry unearthed that incorrectness.

Rewrite it so that all id operations are under the hash lock.

Reported-by: syzbot+5c54bd3eb218bb595aa9@syzkaller.appspotmail.com
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/87bkhzdn6g.ffs@tglx
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/sched/signal.h |  2 +-
 kernel/time/posix-timers.c   | 31 ++++++++++++++++++-------------
 2 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 20099268fa257..669e8cff40c74 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -135,7 +135,7 @@ struct signal_struct {
 #ifdef CONFIG_POSIX_TIMERS
 
 	/* POSIX.1b Interval Timers */
-	int			posix_timer_id;
+	unsigned int		next_posix_timer_id;
 	struct list_head	posix_timers;
 
 	/* ITIMER_REAL timer for the process */
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 808a247205a9a..4431aecb8b12c 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -140,25 +140,30 @@ static struct k_itimer *posix_timer_by_id(timer_t id)
 static int posix_timer_add(struct k_itimer *timer)
 {
 	struct signal_struct *sig = current->signal;
-	int first_free_id = sig->posix_timer_id;
 	struct hlist_head *head;
-	int ret = -ENOENT;
+	unsigned int cnt, id;
 
-	do {
+	/*
+	 * FIXME: Replace this by a per signal struct xarray once there is
+	 * a plan to handle the resulting CRIU regression gracefully.
+	 */
+	for (cnt = 0; cnt <= INT_MAX; cnt++) {
 		spin_lock(&hash_lock);
-		head = &posix_timers_hashtable[hash(sig, sig->posix_timer_id)];
-		if (!__posix_timers_find(head, sig, sig->posix_timer_id)) {
+		id = sig->next_posix_timer_id;
+
+		/* Write the next ID back. Clamp it to the positive space */
+		sig->next_posix_timer_id = (id + 1) & INT_MAX;
+
+		head = &posix_timers_hashtable[hash(sig, id)];
+		if (!__posix_timers_find(head, sig, id)) {
 			hlist_add_head_rcu(&timer->t_hash, head);
-			ret = sig->posix_timer_id;
+			spin_unlock(&hash_lock);
+			return id;
 		}
-		if (++sig->posix_timer_id < 0)
-			sig->posix_timer_id = 0;
-		if ((sig->posix_timer_id == first_free_id) && (ret == -ENOENT))
-			/* Loop over all possible ids completed */
-			ret = -EAGAIN;
 		spin_unlock(&hash_lock);
-	} while (ret == -ENOENT);
-	return ret;
+	}
+	/* POSIX return code when no timer ID could be allocated */
+	return -EAGAIN;
 }
 
 static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
-- 
2.39.2

[PATCH AUTOSEL 6.1 10/12] btrfs: add xxhash to fast checksum implementations

[Sasha Levin]

From: David Sterba <dsterba@suse.com>

[ Upstream commit efcfcbc6a36195c42d98e0ee697baba36da94dc8 ]

The implementation of XXHASH is now CPU only but still fast enough to be
considered for the synchronous checksumming, like non-generic crc32c.

A userspace benchmark comparing it to various implementations (patched
hash-speedtest from btrfs-progs):

  Block size:     4096
  Iterations:     1000000
  Implementation: builtin
  Units:          CPU cycles

	NULL-NOP: cycles:     73384294, cycles/i       73
     NULL-MEMCPY: cycles:    228033868, cycles/i      228,    61664.320 MiB/s
      CRC32C-ref: cycles:  24758559416, cycles/i    24758,      567.950 MiB/s
       CRC32C-NI: cycles:   1194350470, cycles/i     1194,    11773.433 MiB/s
  CRC32C-ADLERSW: cycles:   6150186216, cycles/i     6150,     2286.372 MiB/s
  CRC32C-ADLERHW: cycles:    626979180, cycles/i      626,    22427.453 MiB/s
      CRC32C-PCL: cycles:    466746732, cycles/i      466,    30126.699 MiB/s
	  XXHASH: cycles:    860656400, cycles/i      860,    16338.188 MiB/s

Comparing purely software implementation (ref), current outdated
accelerated using crc32q instruction (NI), optimized implementations by
M. Adler (https://stackoverflow.com/questions/17645167/implementing-sse-4-2s-crc32c-in-software/17646775#17646775)
and the best one that was taken from kernel using the PCLMULQDQ
instruction (PCL).

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/disk-io.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index f22e00dfec6c4..fa44e8f5ccd2c 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2362,6 +2362,9 @@ static int btrfs_init_csum_hash(struct btrfs_fs_info *fs_info, u16 csum_type)
 		if (!strstr(crypto_shash_driver_name(csum_shash), "generic"))
 			set_bit(BTRFS_FS_CSUM_IMPL_FAST, &fs_info->flags);
 		break;
+	case BTRFS_CSUM_TYPE_XXHASH:
+		set_bit(BTRFS_FS_CSUM_IMPL_FAST, &fs_info->flags);
+		break;
 	default:
 		break;
 	}
-- 
2.39.2

[PATCH AUTOSEL 6.1 11/12] btrfs: don't check PageError in __extent_writepage

[Sasha Levin]

From: Christoph Hellwig <hch@lst.de>

[ Upstream commit 3e92499e3b004baffb479d61e191b41b604ece9a ]

__extent_writepage currenly sets PageError whenever any error happens,
and the also checks for PageError to decide if to call error handling.
This leads to very unclear responsibility for cleaning up on errors.
In the VM and generic writeback helpers the basic idea is that once
I/O is fired off all error handling responsibility is delegated to the
end I/O handler.  But if that end I/O handler sets the PageError bit,
and the submitter checks it, the bit could in some cases leak into the
submission context for fast enough I/O.

Fix this by simply not checking PageError and just using the local
ret variable to check for submission errors.  This also fundamentally
solves the long problem documented in a comment in __extent_writepage
by never leaking the error bit into the submission context.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/extent_io.c | 33 +--------------------------------
 1 file changed, 1 insertion(+), 32 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 58785dc7080ad..ce4d87fd9a213 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2296,38 +2296,7 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc,
 		set_page_writeback(page);
 		end_page_writeback(page);
 	}
-	/*
-	 * Here we used to have a check for PageError() and then set @ret and
-	 * call end_extent_writepage().
-	 *
-	 * But in fact setting @ret here will cause different error paths
-	 * between subpage and regular sectorsize.
-	 *
-	 * For regular page size, we never submit current page, but only add
-	 * current page to current bio.
-	 * The bio submission can only happen in next page.
-	 * Thus if we hit the PageError() branch, @ret is already set to
-	 * non-zero value and will not get updated for regular sectorsize.
-	 *
-	 * But for subpage case, it's possible we submit part of current page,
-	 * thus can get PageError() set by submitted bio of the same page,
-	 * while our @ret is still 0.
-	 *
-	 * So here we unify the behavior and don't set @ret.
-	 * Error can still be properly passed to higher layer as page will
-	 * be set error, here we just don't handle the IO failure.
-	 *
-	 * NOTE: This is just a hotfix for subpage.
-	 * The root fix will be properly ending ordered extent when we hit
-	 * an error during writeback.
-	 *
-	 * But that needs a bigger refactoring, as we not only need to grab the
-	 * submitted OE, but also need to know exactly at which bytenr we hit
-	 * the error.
-	 * Currently the full page based __extent_writepage_io() is not
-	 * capable of that.
-	 */
-	if (PageError(page))
+	if (ret)
 		end_extent_writepage(page, ret, page_start, page_end);
 	if (epd->extent_locked) {
 		/*
-- 
2.39.2

[PATCH AUTOSEL 6.1 12/12] btrfs: abort transaction at update_ref_for_cow() when ref count is zero

[Sasha Levin]

From: Filipe Manana <fdmanana@suse.com>

[ Upstream commit eced687e224eb3cc5a501cf53ad9291337c8dbc5 ]

At update_ref_for_cow() we are calling btrfs_handle_fs_error() if we find
that the extent buffer has an unexpected ref count of zero, however we can
simply use btrfs_abort_transaction(), which achieves the same purposes: to
turn the fs to error state, abort the current transaction and turn the fs
to RO mode as well. Besides that, btrfs_abort_transaction() also prints a
stack trace which makes it more useful.

Also, as this is a very unexpected situation, indicating a serious
corruption/inconsistency, tag the if branch as 'unlikely', set the error
code to -EUCLEAN instead of -EROFS, and log an explicit message.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/ctree.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index ab9f8d6c4f1b9..5d462dd5fcf56 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -309,9 +309,13 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 					       &refs, &flags);
 		if (ret)
 			return ret;
-		if (refs == 0) {
-			ret = -EROFS;
-			btrfs_handle_fs_error(fs_info, ret, NULL);
+		if (unlikely(refs == 0)) {
+			btrfs_crit(fs_info,
+		"found 0 references for tree block at bytenr %llu level %d root %llu",
+				   buf->start, btrfs_header_level(buf),
+				   btrfs_root_id(root));
+			ret = -EUCLEAN;
+			btrfs_abort_transaction(trans, ret);
 			return ret;
 		}
 	} else {
-- 
2.39.2