When doing an atomic modeset with ALLOW_MODESET drivers are allowed to
pull in arbitrary other resources, including CRTCs (e.g. when
reconfiguring global resources).
But in nonblocking mode userspace has then no idea this happened,
which can lead to spurious EBUSY calls, both:
- when that other CRTC is currently busy doing a page_flip the
ALLOW_MODESET commit can fail with an EBUSY
- on the other CRTC a normal atomic flip can fail with EBUSY because
of the additional commit inserted by the kernel without userspace's
knowledge
For blocking commits this isn't a problem, because everyone else will
just block until all the CRTC are reconfigured. Only thing userspace
can notice is the dropped frames without any reason for why frames got
dropped.
Consensus is that we need new uapi to handle this properly, but no one
has any idea what exactly the new uapi should look like. As a stop-gap
plug this problem by demoting nonblocking commits which might cause
issues by including CRTCs not in the original request to blocking
commits.
v2: Add comments and a WARN_ON to enforce this only when allowed - we
don't want to silently convert page flips into blocking plane updates
just because the driver is buggy.
References: https://lists.freedesktop.org/archives/dri-devel/2018-July/182281.html
Bugzilla: https://gitlab.freedesktop.org/wayland/weston/issues/24#note_9568
Cc: Daniel Stone <daniel(a)fooishbar.org>
Cc: Pekka Paalanen <pekka.paalanen(a)collabora.co.uk>
Cc: stable(a)vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter(a)intel.com>
---
drivers/gpu/drm/drm_atomic.c | 34 +++++++++++++++++++++++++++++++---
1 file changed, 31 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index d5cefb1cb2a2..058512f14772 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -2018,15 +2018,43 @@ EXPORT_SYMBOL(drm_atomic_commit);
int drm_atomic_nonblocking_commit(struct drm_atomic_state *state)
{
struct drm_mode_config *config = &state->dev->mode_config;
- int ret;
+ unsigned requested_crtc = 0;
+ unsigned affected_crtc = 0;
+ struct drm_crtc *crtc;
+ struct drm_crtc_state *crtc_state;
+ bool nonblocking = true;
+ int ret, i;
+
+ /*
+ * For commits that allow modesets drivers can add other CRTCs to the
+ * atomic commit, e.g. when they need to reallocate global resources.
+ *
+ * But when userspace also requests a nonblocking commit then userspace
+ * cannot know that the commit affects other CRTCs, which can result in
+ * spurious EBUSY failures. Until we have better uapi plug this by
+ * demoting such commits to blocking mode.
+ */
+ for_each_new_crtc_in_state(state, crtc, crtc_state, i)
+ requested_crtc |= drm_crtc_mask(crtc);
ret = drm_atomic_check_only(state);
if (ret)
return ret;
- DRM_DEBUG_ATOMIC("committing %p nonblocking\n", state);
+ for_each_new_crtc_in_state(state, crtc, crtc_state, i)
+ affected_crtc |= drm_crtc_mask(crtc);
+
+ if (affected_crtc != requested_crtc) {
+ /* adding other CRTC is only allowed for modeset commits */
+ WARN_ON(state->allow_modeset);
+
+ DRM_DEBUG_ATOMIC("demoting %p to blocking mode to avoid EBUSY\n", state);
+ nonblocking = false;
+ } else {
+ DRM_DEBUG_ATOMIC("committing %p nonblocking\n", state);
+ }
- return config->funcs->atomic_commit(state->dev, state, true);
+ return config->funcs->atomic_commit(state->dev, state, nonblocking);
}
EXPORT_SYMBOL(drm_atomic_nonblocking_commit);
--
2.18.0
The premature free in the error path is blocked by V4L
refcounting, not USB refcounting. Thanks to
Ben Hutchings for review.
[v2] corrected attributions
Signed-off-by: Oliver Neukum <oneukum(a)suse.com>
Fixes: 50e704453553 ("media: usbtv: prevent double free in error case")
CC: stable(a)vger.kernel.org
Reported-by: Ben Hutchings <ben.hutchings(a)codethink.co.uk>
---
drivers/media/usb/usbtv/usbtv-core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/media/usb/usbtv/usbtv-core.c b/drivers/media/usb/usbtv/usbtv-core.c
index 5095c380b2c1..4a03c4d66314 100644
--- a/drivers/media/usb/usbtv/usbtv-core.c
+++ b/drivers/media/usb/usbtv/usbtv-core.c
@@ -113,7 +113,8 @@ static int usbtv_probe(struct usb_interface *intf,
usbtv_audio_fail:
/* we must not free at this point */
- usb_get_dev(usbtv->udev);
+ v4l2_device_get(&usbtv->v4l2_dev);
+ /* this will undo the v4l2_device_get() */
usbtv_video_free(usbtv);
usbtv_video_fail:
--
2.13.6
Commit 9c8088c7988 ("i2c: i801: Don't restore config registers on
runtime PM") nullified the runtime PM suspend/resume callback pointers
while keeping the runtime PM enabled. This causes that device stays in
D0 power state and sysfs /sys/bus/pci/devices/.../power/runtime_status
shows "error" when runtime PM framework attempts to autosuspend the
device.
This is due PCI bus runtime PM which checks for driver runtime PM
callbacks and returns with -ENOSYS if they are not set. Fix this by
having a shared dummy runtime PM callback that returns with success.
Fixes: a9c8088c7988 ("i2c: i801: Don't restore config registers on runtime PM")
Reported-by: Mika Westerberg <mika.westerberg(a)linux.intel.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Jarkko Nikula <jarkko.nikula(a)linux.intel.com>
---
drivers/i2c/busses/i2c-i801.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index aa726607645e..3747484c2669 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -1731,7 +1731,20 @@ static int i801_resume(struct device *dev)
}
#endif
-static SIMPLE_DEV_PM_OPS(i801_pm_ops, i801_suspend, i801_resume);
+static int __maybe_unused i801_runtime_nop(struct device *dev)
+{
+ /*
+ * PCI core expects runtime PM suspend/resume callbacks return
+ * successfully before really suspending/resuming the device.
+ * Have a shared dummy callback that returns with success.
+ */
+ return 0;
+}
+
+static const struct dev_pm_ops i801_pm_ops = {
+ SET_SYSTEM_SLEEP_PM_OPS(i801_suspend, i801_resume)
+ SET_RUNTIME_PM_OPS(i801_runtime_nop, i801_runtime_nop, NULL)
+};
static struct pci_driver i801_driver = {
.name = "i801_smbus",
--
2.18.0
fuse_dev_splice_write() reads pipe->buffers to determine the size of
'bufs' array before taking the pipe_lock(). This is not safe as
another thread might change the 'pipe->buffers' between the allocation
and taking the pipe_lock(). So we end up with too small 'bufs' array.
Move the bufs allocations inside pipe_lock()/pipe_unlock() to fix this.
Fixes: dd3bb14f44a6 ("fuse: support splice() writing to fuse device")
Signed-off-by: Andrey Ryabinin <aryabinin(a)virtuozzo.com>
Cc: <stable(a)vger.kernel.org>
---
fs/fuse/dev.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index c6b88fa85e2e..702592cce546 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1944,12 +1944,15 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
if (!fud)
return -EPERM;
+ pipe_lock(pipe);
+
bufs = kmalloc_array(pipe->buffers, sizeof(struct pipe_buffer),
GFP_KERNEL);
- if (!bufs)
+ if (!bufs) {
+ pipe_unlock(pipe);
return -ENOMEM;
+ }
- pipe_lock(pipe);
nbuf = 0;
rem = 0;
for (idx = 0; idx < pipe->nrbufs && rem < len; idx++)
--
2.16.4
The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 432061b3da64e488be3403124a72a9250bbe96d4 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka(a)redhat.com>
Date: Wed, 5 Sep 2018 09:17:45 -0400
Subject: [PATCH] dm: disable CRYPTO_TFM_REQ_MAY_SLEEP to fix a GFP_KERNEL
recursion deadlock
There's a XFS on dm-crypt deadlock, recursing back to itself due to the
crypto subsystems use of GFP_KERNEL, reported here:
https://bugzilla.kernel.org/show_bug.cgi?id=200835
* dm-crypt calls crypt_convert in xts mode
* init_crypt from xts.c calls kmalloc(GFP_KERNEL)
* kmalloc(GFP_KERNEL) recurses into the XFS filesystem, the filesystem
tries to submit some bios and wait for them, causing a deadlock
Fix this by updating both the DM crypt and integrity targets to no
longer use the CRYPTO_TFM_REQ_MAY_SLEEP flag, which will change the
crypto allocations from GFP_KERNEL to GFP_ATOMIC, therefore they can't
recurse into a filesystem. A GFP_ATOMIC allocation can fail, but
init_crypt() in xts.c handles the allocation failure gracefully - it
will fall back to preallocated buffer if the allocation fails.
The crypto API maintainer says that the crypto API only needs to
allocate memory when dealing with unaligned buffers and therefore
turning CRYPTO_TFM_REQ_MAY_SLEEP off is safe (see this discussion:
https://www.redhat.com/archives/dm-devel/2018-August/msg00195.html )
Cc: stable(a)vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka(a)redhat.com>
Signed-off-by: Mike Snitzer <snitzer(a)redhat.com>
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index f266c81f396f..0481223b1deb 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -332,7 +332,7 @@ static int crypt_iv_essiv_init(struct crypt_config *cc)
int err;
desc->tfm = essiv->hash_tfm;
- desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+ desc->flags = 0;
err = crypto_shash_digest(desc, cc->key, cc->key_size, essiv->salt);
shash_desc_zero(desc);
@@ -606,7 +606,7 @@ static int crypt_iv_lmk_one(struct crypt_config *cc, u8 *iv,
int i, r;
desc->tfm = lmk->hash_tfm;
- desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+ desc->flags = 0;
r = crypto_shash_init(desc);
if (r)
@@ -768,7 +768,7 @@ static int crypt_iv_tcw_whitening(struct crypt_config *cc,
/* calculate crc32 for every 32bit part and xor it */
desc->tfm = tcw->crc32_tfm;
- desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+ desc->flags = 0;
for (i = 0; i < 4; i++) {
r = crypto_shash_init(desc);
if (r)
@@ -1251,7 +1251,7 @@ static void crypt_alloc_req_skcipher(struct crypt_config *cc,
* requests if driver request queue is full.
*/
skcipher_request_set_callback(ctx->r.req,
- CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+ CRYPTO_TFM_REQ_MAY_BACKLOG,
kcryptd_async_done, dmreq_of_req(cc, ctx->r.req));
}
@@ -1268,7 +1268,7 @@ static void crypt_alloc_req_aead(struct crypt_config *cc,
* requests if driver request queue is full.
*/
aead_request_set_callback(ctx->r.req_aead,
- CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+ CRYPTO_TFM_REQ_MAY_BACKLOG,
kcryptd_async_done, dmreq_of_req(cc, ctx->r.req_aead));
}
diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 378878599466..89ccb64342de 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -532,7 +532,7 @@ static void section_mac(struct dm_integrity_c *ic, unsigned section, __u8 result
unsigned j, size;
desc->tfm = ic->journal_mac;
- desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+ desc->flags = 0;
r = crypto_shash_init(desc);
if (unlikely(r)) {
@@ -676,7 +676,7 @@ static void complete_journal_encrypt(struct crypto_async_request *req, int err)
static bool do_crypt(bool encrypt, struct skcipher_request *req, struct journal_completion *comp)
{
int r;
- skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+ skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
complete_journal_encrypt, comp);
if (likely(encrypt))
r = crypto_skcipher_encrypt(req);
c2856ae2f315d ("blk-mq: quiesce queue before freeing queue") has
already fixed this race, however the implied synchronize_rcu()
in blk_mq_quiesce_queue() can slow down LUN probe a lot, so caused
performance regression.
Then 1311326cf4755c7 ("blk-mq: avoid to synchronize rcu inside blk_cleanup_queue()")
tried to quiesce queue for avoiding unnecessary synchronize_rcu()
only when queue initialization is done, because it is usual to see
lots of inexistent LUNs which need to be probed.
However, turns out it isn't safe to quiesce queue only when queue
initialization is done. Because when one SCSI command is completed,
the user of sending command can be waken up immediately, then the
scsi device may be removed, meantime the run queue in scsi_end_request()
is still in-progress, so kernel panic can be caused.
In Red Hat QE lab, there are several reports about this kind of kernel
panic triggered during kernel booting.
This patch tries to address the issue by grabing one queue usage
counter during freeing one request and the following run queue.
Fixes: 1311326cf4755c7 ("blk-mq: avoid to synchronize rcu inside blk_cleanup_queue()")
Cc: Andrew Jones <drjones(a)redhat.com>
Cc: Bart Van Assche <bart.vanassche(a)wdc.com>
Cc: linux-scsi(a)vger.kernel.org
Cc: Martin K. Petersen <martin.petersen(a)oracle.com>
Cc: Christoph Hellwig <hch(a)lst.de>
Cc: James E.J. Bottomley <jejb(a)linux.vnet.ibm.com>
Cc: stable <stable(a)vger.kernel.org>
Cc: jianchao.wang <jianchao.w.wang(a)oracle.com>
Signed-off-by: Ming Lei <ming.lei(a)redhat.com>
---
block/blk-core.c | 5 ++---
drivers/scsi/scsi_lib.c | 8 ++++++++
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index ce12515f9b9b..deb56932f8c4 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -798,9 +798,8 @@ void blk_cleanup_queue(struct request_queue *q)
* dispatch may still be in-progress since we dispatch requests
* from more than one contexts.
*
- * No need to quiesce queue if it isn't initialized yet since
- * blk_freeze_queue() should be enough for cases of passthrough
- * request.
+ * We rely on driver to deal with the race in case that queue
+ * initialization isn't done.
*/
if (q->mq_ops && blk_queue_init_done(q))
blk_mq_quiesce_queue(q);
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index c7fccbb8f554..fa6e0c3b3aa6 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -697,6 +697,12 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
*/
scsi_mq_uninit_cmd(cmd);
+ /*
+ * queue is still alive, so grab the ref for preventing it
+ * from being cleaned up during running queue.
+ */
+ percpu_ref_get(&q->q_usage_counter);
+
__blk_mq_end_request(req, error);
if (scsi_target(sdev)->single_lun ||
@@ -704,6 +710,8 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
kblockd_schedule_work(&sdev->requeue_work);
else
blk_mq_run_hw_queues(q, true);
+
+ percpu_ref_put(&q->q_usage_counter);
} else {
unsigned long flags;
--
2.9.5