[PATCH v3 0/5] Backport of patch series for stable 4.4 branch

[PATCH v3 0/5] Backport of patch series for stable 4.4 branch

[SeongJae Park]

From: SeongJae Park <sjpark@amazon.de>

Changes from v2
(https://lore.kernel.org/stable/20201217130501.12702-1-sjpark@amazon.com/)
- Move 'nr_pending' increase from 5th patch to 4th patch

Changes from v1
(https://lore.kernel.org/stable/20201217081727.8253-1-sjpark@amazon.com/)
- Remove wrong 'Signed-off-by' lines for 'Author Redacted'


SeongJae Park (5):
  xen/xenbus: Allow watches discard events before queueing
  xen/xenbus: Add 'will_handle' callback support in xenbus_watch_path()
  xen/xenbus/xen_bus_type: Support will_handle watch callback
  xen/xenbus: Count pending messages for each watch
  xenbus/xenbus_backend: Disallow pending watch messages

 drivers/block/xen-blkback/xenbus.c        |  3 +-
 drivers/net/xen-netback/xenbus.c          |  4 ++-
 drivers/xen/xen-pciback/xenbus.c          |  2 +-
 drivers/xen/xenbus/xenbus_client.c        |  8 ++++-
 drivers/xen/xenbus/xenbus_probe.c         |  1 +
 drivers/xen/xenbus/xenbus_probe.h         |  2 ++
 drivers/xen/xenbus/xenbus_probe_backend.c |  7 +++++
 drivers/xen/xenbus/xenbus_xs.c            | 38 +++++++++++++++--------
 include/xen/xenbus.h                      | 15 ++++++++-
 9 files changed, 62 insertions(+), 18 deletions(-)

-- 
2.17.1

[PATCH v3 1/5] xen/xenbus: Allow watches discard events before queueing

[SeongJae Park]

From: SeongJae Park <sjpark@amazon.de>

If handling logics of watch events are slower than the events enqueue
logic and the events can be created from the guests, the guests could
trigger memory pressure by intensively inducing the events, because it
will create a huge number of pending events that exhausting the memory.
This is known as XSA-349.

Fortunately, some watch events could be ignored, depending on its
handler callback.  For example, if the callback has interest in only one
single path, the watch wouldn't want multiple pending events.  Or, some
watches could ignore events to same path.

To let such watches to volutarily help avoiding the memory pressure
situation, this commit introduces new watch callback, 'will_handle'.  If
it is not NULL, it will be called for each new event just before
enqueuing it.  Then, if the callback returns false, the event will be
discarded.  No watch is using the callback for now, though.

This is part of XSA-349

This is upstream commit fed1755b118147721f2c87b37b9d66e62c39b668

Cc: stable@vger.kernel.org
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reported-by: Michael Kurth <mku@amazon.de>
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/net/xen-netback/xenbus.c   | 2 ++
 drivers/xen/xenbus/xenbus_client.c | 1 +
 drivers/xen/xenbus/xenbus_xs.c     | 7 ++++++-
 include/xen/xenbus.h               | 7 +++++++
 4 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 56ebd8267386..23f03af0a2d4 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -697,12 +697,14 @@ static int xen_register_watchers(struct xenbus_device *dev, struct xenvif *vif)
 		return -ENOMEM;
 	snprintf(node, maxlen, "%s/rate", dev->nodename);
 	vif->credit_watch.node = node;
+	vif->credit_watch.will_handle = NULL;
 	vif->credit_watch.callback = xen_net_rate_changed;
 	err = register_xenbus_watch(&vif->credit_watch);
 	if (err) {
 		pr_err("Failed to set watcher %s\n", vif->credit_watch.node);
 		kfree(node);
 		vif->credit_watch.node = NULL;
+		vif->credit_watch.will_handle = NULL;
 		vif->credit_watch.callback = NULL;
 	}
 	return err;
diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index 266f446ba331..d02d25f784c9 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -120,6 +120,7 @@ int xenbus_watch_path(struct xenbus_device *dev, const char *path,
 	int err;
 
 	watch->node = path;
+	watch->will_handle = NULL;
 	watch->callback = callback;
 
 	err = register_xenbus_watch(watch);
diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c
index ce65591b4168..0ea1c259f2f1 100644
--- a/drivers/xen/xenbus/xenbus_xs.c
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -903,7 +903,12 @@ static int process_msg(void)
 		spin_lock(&watches_lock);
 		msg->u.watch.handle = find_watch(
 			msg->u.watch.vec[XS_WATCH_TOKEN]);
-		if (msg->u.watch.handle != NULL) {
+		if (msg->u.watch.handle != NULL &&
+				(!msg->u.watch.handle->will_handle ||
+				 msg->u.watch.handle->will_handle(
+					 msg->u.watch.handle,
+					 (const char **)msg->u.watch.vec,
+					 msg->u.watch.vec_size))) {
 			spin_lock(&watch_events_lock);
 			list_add_tail(&msg->list, &watch_events);
 			wake_up(&watch_events_waitq);
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index 32b944b7cebd..11697aa023b5 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -58,6 +58,13 @@ struct xenbus_watch
 	/* Path being watched. */
 	const char *node;
 
+	/*
+	 * Called just before enqueing new event while a spinlock is held.
+	 * The event will be discarded if this callback returns false.
+	 */
+	bool (*will_handle)(struct xenbus_watch *,
+			    const char **vec, unsigned int len);
+
 	/* Callback (executed in a process context with no locks held). */
 	void (*callback)(struct xenbus_watch *,
 			 const char **vec, unsigned int len);
-- 
2.17.1

[PATCH v3 2/5] xen/xenbus: Add 'will_handle' callback support in xenbus_watch_path()

[SeongJae Park]

From: SeongJae Park <sjpark@amazon.de>

Some code does not directly make 'xenbus_watch' object and call
'register_xenbus_watch()' but use 'xenbus_watch_path()' instead.  This
commit adds support of 'will_handle' callback in the
'xenbus_watch_path()' and it's wrapper, 'xenbus_watch_pathfmt()'.

This is part of XSA-349

This is upstream commit 2e85d32b1c865bec703ce0c962221a5e955c52c2

Cc: stable@vger.kernel.org
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reported-by: Michael Kurth <mku@amazon.de>
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/block/xen-blkback/xenbus.c | 3 ++-
 drivers/net/xen-netback/xenbus.c   | 2 +-
 drivers/xen/xen-pciback/xenbus.c   | 2 +-
 drivers/xen/xenbus/xenbus_client.c | 9 +++++++--
 drivers/xen/xenbus/xenbus_probe.c  | 2 +-
 include/xen/xenbus.h               | 6 +++++-
 6 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 0ec257e69e95..823f3480ebd1 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -553,7 +553,8 @@ static int xen_blkbk_probe(struct xenbus_device *dev,
 	/* setup back pointer */
 	be->blkif->be = be;
 
-	err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed,
+	err = xenbus_watch_pathfmt(dev, &be->backend_watch, NULL,
+				   backend_changed,
 				   "%s/%s", dev->nodename, "physical-device");
 	if (err)
 		goto fail;
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 23f03af0a2d4..21c8e2720b40 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -849,7 +849,7 @@ static void connect(struct backend_info *be)
 	xenvif_carrier_on(be->vif);
 
 	unregister_hotplug_status_watch(be);
-	err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
+	err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch, NULL,
 				   hotplug_status_changed,
 				   "%s/%s", dev->nodename, "hotplug-status");
 	if (!err)
diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index 48196347f2f9..12497a2140c2 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -691,7 +691,7 @@ static int xen_pcibk_xenbus_probe(struct xenbus_device *dev,
 
 	/* watch the backend node for backend configuration information */
 	err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
-				xen_pcibk_be_watch);
+				NULL, xen_pcibk_be_watch);
 	if (err)
 		goto out;
 
diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index d02d25f784c9..8bbd887ca422 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -114,19 +114,22 @@ EXPORT_SYMBOL_GPL(xenbus_strstate);
  */
 int xenbus_watch_path(struct xenbus_device *dev, const char *path,
 		      struct xenbus_watch *watch,
+		      bool (*will_handle)(struct xenbus_watch *,
+					  const char **, unsigned int),
 		      void (*callback)(struct xenbus_watch *,
 				       const char **, unsigned int))
 {
 	int err;
 
 	watch->node = path;
-	watch->will_handle = NULL;
+	watch->will_handle = will_handle;
 	watch->callback = callback;
 
 	err = register_xenbus_watch(watch);
 
 	if (err) {
 		watch->node = NULL;
+		watch->will_handle = NULL;
 		watch->callback = NULL;
 		xenbus_dev_fatal(dev, err, "adding watch on %s", path);
 	}
@@ -153,6 +156,8 @@ EXPORT_SYMBOL_GPL(xenbus_watch_path);
  */
 int xenbus_watch_pathfmt(struct xenbus_device *dev,
 			 struct xenbus_watch *watch,
+			 bool (*will_handle)(struct xenbus_watch *,
+					     const char **, unsigned int),
 			 void (*callback)(struct xenbus_watch *,
 					const char **, unsigned int),
 			 const char *pathfmt, ...)
@@ -169,7 +174,7 @@ int xenbus_watch_pathfmt(struct xenbus_device *dev,
 		xenbus_dev_fatal(dev, -ENOMEM, "allocating path for watch");
 		return -ENOMEM;
 	}
-	err = xenbus_watch_path(dev, path, watch, callback);
+	err = xenbus_watch_path(dev, path, watch, will_handle, callback);
 
 	if (err)
 		kfree(path);
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index c2d447687e33..c560c1b8489a 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -137,7 +137,7 @@ static int watch_otherend(struct xenbus_device *dev)
 		container_of(dev->dev.bus, struct xen_bus_type, bus);
 
 	return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
-				    bus->otherend_changed,
+				    NULL, bus->otherend_changed,
 				    "%s/%s", dev->otherend, "state");
 }
 
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index 11697aa023b5..1772507dc2c9 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -201,10 +201,14 @@ void xenbus_suspend_cancel(void);
 
 int xenbus_watch_path(struct xenbus_device *dev, const char *path,
 		      struct xenbus_watch *watch,
+		      bool (*will_handle)(struct xenbus_watch *,
+					  const char **, unsigned int),
 		      void (*callback)(struct xenbus_watch *,
 				       const char **, unsigned int));
-__printf(4, 5)
+__printf(5, 6)
 int xenbus_watch_pathfmt(struct xenbus_device *dev, struct xenbus_watch *watch,
+			 bool (*will_handle)(struct xenbus_watch *,
+					     const char **, unsigned int),
 			 void (*callback)(struct xenbus_watch *,
 					  const char **, unsigned int),
 			 const char *pathfmt, ...);
-- 
2.17.1

[PATCH v3 3/5] xen/xenbus/xen_bus_type: Support will_handle watch callback

[SeongJae Park]

From: SeongJae Park <sjpark@amazon.de>

This commit adds support of the 'will_handle' watch callback for
'xen_bus_type' users.

This is part of XSA-349

This is upstream commit be987200fbaceaef340872841d4f7af2c5ee8dc3

Cc: stable@vger.kernel.org
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reported-by: Michael Kurth <mku@amazon.de>
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/xenbus/xenbus_probe.c | 3 ++-
 drivers/xen/xenbus/xenbus_probe.h | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index c560c1b8489a..ba7590d75985 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -137,7 +137,8 @@ static int watch_otherend(struct xenbus_device *dev)
 		container_of(dev->dev.bus, struct xen_bus_type, bus);
 
 	return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
-				    NULL, bus->otherend_changed,
+				    bus->otherend_will_handle,
+				    bus->otherend_changed,
 				    "%s/%s", dev->otherend, "state");
 }
 
diff --git a/drivers/xen/xenbus/xenbus_probe.h b/drivers/xen/xenbus/xenbus_probe.h
index c9ec7ca1f7ab..2c394c6ba605 100644
--- a/drivers/xen/xenbus/xenbus_probe.h
+++ b/drivers/xen/xenbus/xenbus_probe.h
@@ -42,6 +42,8 @@ struct xen_bus_type {
 	int (*get_bus_id)(char bus_id[XEN_BUS_ID_SIZE], const char *nodename);
 	int (*probe)(struct xen_bus_type *bus, const char *type,
 		     const char *dir);
+	bool (*otherend_will_handle)(struct xenbus_watch *watch,
+				     const char **vec, unsigned int len);
 	void (*otherend_changed)(struct xenbus_watch *watch, const char **vec,
 				 unsigned int len);
 	struct bus_type bus;
-- 
2.17.1

[PATCH v3 4/5] xen/xenbus: Count pending messages for each watch

[SeongJae Park]

From: SeongJae Park <sjpark@amazon.de>

This commit adds a counter of pending messages for each watch in the
struct.  It is used to skip unnecessary pending messages lookup in
'unregister_xenbus_watch()'.  It could also be used in 'will_handle'
callback.

This is part of XSA-349

This is upstream commit 3dc86ca6b4c8cfcba9da7996189d1b5a358a94fc

Cc: stable@vger.kernel.org
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reported-by: Michael Kurth <mku@amazon.de>
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/xenbus/xenbus_xs.c | 31 +++++++++++++++++++------------
 include/xen/xenbus.h           |  2 ++
 2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c
index 0ea1c259f2f1..d98d88fae58a 100644
--- a/drivers/xen/xenbus/xenbus_xs.c
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -701,6 +701,8 @@ int register_xenbus_watch(struct xenbus_watch *watch)
 
 	sprintf(token, "%lX", (long)watch);
 
+	watch->nr_pending = 0;
+
 	down_read(&xs_state.watch_mutex);
 
 	spin_lock(&watches_lock);
@@ -750,12 +752,15 @@ void unregister_xenbus_watch(struct xenbus_watch *watch)
 
 	/* Cancel pending watch events. */
 	spin_lock(&watch_events_lock);
-	list_for_each_entry_safe(msg, tmp, &watch_events, list) {
-		if (msg->u.watch.handle != watch)
-			continue;
-		list_del(&msg->list);
-		kfree(msg->u.watch.vec);
-		kfree(msg);
+	if (watch->nr_pending) {
+		list_for_each_entry_safe(msg, tmp, &watch_events, list) {
+			if (msg->u.watch.handle != watch)
+				continue;
+			list_del(&msg->list);
+			kfree(msg->u.watch.vec);
+			kfree(msg);
+		}
+		watch->nr_pending = 0;
 	}
 	spin_unlock(&watch_events_lock);
 
@@ -802,7 +807,6 @@ void xs_suspend_cancel(void)
 
 static int xenwatch_thread(void *unused)
 {
-	struct list_head *ent;
 	struct xs_stored_msg *msg;
 
 	for (;;) {
@@ -815,13 +819,15 @@ static int xenwatch_thread(void *unused)
 		mutex_lock(&xenwatch_mutex);
 
 		spin_lock(&watch_events_lock);
-		ent = watch_events.next;
-		if (ent != &watch_events)
-			list_del(ent);
+		msg = list_first_entry_or_null(&watch_events,
+				struct xs_stored_msg, list);
+		if (msg) {
+			list_del(&msg->list);
+			msg->u.watch.handle->nr_pending--;
+		}
 		spin_unlock(&watch_events_lock);
 
-		if (ent != &watch_events) {
-			msg = list_entry(ent, struct xs_stored_msg, list);
+		if (msg) {
 			msg->u.watch.handle->callback(
 				msg->u.watch.handle,
 				(const char **)msg->u.watch.vec,
@@ -911,6 +917,7 @@ static int process_msg(void)
 					 msg->u.watch.vec_size))) {
 			spin_lock(&watch_events_lock);
 			list_add_tail(&msg->list, &watch_events);
+			msg->u.watch.handle->nr_pending++;
 			wake_up(&watch_events_waitq);
 			spin_unlock(&watch_events_lock);
 		} else {
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index 1772507dc2c9..ed9e7e3307b7 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -58,6 +58,8 @@ struct xenbus_watch
 	/* Path being watched. */
 	const char *node;
 
+	unsigned int nr_pending;
+
 	/*
 	 * Called just before enqueing new event while a spinlock is held.
 	 * The event will be discarded if this callback returns false.
-- 
2.17.1

[PATCH v3 5/5] xenbus/xenbus_backend: Disallow pending watch messages

[SeongJae Park]

From: SeongJae Park <sjpark@amazon.de>

'xenbus_backend' watches 'state' of devices, which is writable by
guests.  Hence, if guests intensively updates it, dom0 will have lots of
pending events that exhausting memory of dom0.  In other words, guests
can trigger dom0 memory pressure.  This is known as XSA-349.  However,
the watch callback of it, 'frontend_changed()', reads only 'state', so
doesn't need to have the pending events.

To avoid the problem, this commit disallows pending watch messages for
'xenbus_backend' using the 'will_handle()' watch callback.

This is part of XSA-349

This is upstream commit 9996bd494794a2fe393e97e7a982388c6249aa76

Cc: stable@vger.kernel.org
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reported-by: Michael Kurth <mku@amazon.de>
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/xenbus/xenbus_probe_backend.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c
index 04f7f85a5edf..597c0b038454 100644
--- a/drivers/xen/xenbus/xenbus_probe_backend.c
+++ b/drivers/xen/xenbus/xenbus_probe_backend.c
@@ -181,6 +181,12 @@ static int xenbus_probe_backend(struct xen_bus_type *bus, const char *type,
 	return err;
 }
 
+static bool frontend_will_handle(struct xenbus_watch *watch,
+				 const char **vec, unsigned int len)
+{
+	return watch->nr_pending == 0;
+}
+
 static void frontend_changed(struct xenbus_watch *watch,
 			    const char **vec, unsigned int len)
 {
@@ -192,6 +198,7 @@ static struct xen_bus_type xenbus_backend = {
 	.levels = 3,		/* backend/type/<frontend>/<id> */
 	.get_bus_id = backend_bus_id,
 	.probe = xenbus_probe_backend,
+	.otherend_will_handle = frontend_will_handle,
 	.otherend_changed = frontend_changed,
 	.bus = {
 		.name		= "xen-backend",
-- 
2.17.1

Re: [PATCH v3 0/5] Backport of patch series for stable 4.4 branch

[Greg KH]

On Thu, Dec 17, 2020 at 05:03:57PM +0100, SeongJae Park wrote:
> From: SeongJae Park <sjpark@amazon.de>
> 
> Changes from v2
> (https://lore.kernel.org/stable/20201217130501.12702-1-sjpark@amazon.com/)
> - Move 'nr_pending' increase from 5th patch to 4th patch
> 
> Changes from v1
> (https://lore.kernel.org/stable/20201217081727.8253-1-sjpark@amazon.com/)
> - Remove wrong 'Signed-off-by' lines for 'Author Redacted'

All now queued up, but you also need a series of this for the 4.9.y tree
as well.

thanks,

greg k-h

Re: [PATCH v3 0/5] Backport of patch series for stable 4.4 branch

[SeongJae Park]

Hi Greg,

On Mon, 28 Dec 2020 12:29:11 +0100 Greg KH <gregkh@linuxfoundation.org> wrote:

> On Thu, Dec 17, 2020 at 05:03:57PM +0100, SeongJae Park wrote:
> > From: SeongJae Park <sjpark@amazon.de>
> > 
> > Changes from v2
> > (https://lore.kernel.org/stable/20201217130501.12702-1-sjpark@amazon.com/)
> > - Move 'nr_pending' increase from 5th patch to 4th patch
> > 
> > Changes from v1
> > (https://lore.kernel.org/stable/20201217081727.8253-1-sjpark@amazon.com/)
> > - Remove wrong 'Signed-off-by' lines for 'Author Redacted'
> 
> All now queued up, but you also need a series of this for the 4.9.y tree
> as well.

Thank you for your efforts!

However, I was able to cherry-pick this series, which is already merged in
4.4.y, to 4.9.y without conflicts.

    $ git checkout stable/linux-4.9.y -b xsa349_4.9
    $ git cherry-pick d8b0d52e408ca..3c71d2f637c8
    warning: inexact rename detection was skipped due to too many files.
    warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
    [xsa349_4.9 51b4cb3db28a] xen/xenbus: Allow watches discard events before queueing
     Date: Mon Dec 14 10:02:45 2020 +0100
     4 files changed, 16 insertions(+), 1 deletion(-)
    warning: inexact rename detection was skipped due to too many files.
    warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
    [xsa349_4.9 3242225d9645] xen/xenbus: Add 'will_handle' callback support in xenbus_watch_path()
     Date: Mon Dec 14 10:04:18 2020 +0100
     6 files changed, 17 insertions(+), 7 deletions(-)
    warning: inexact rename detection was skipped due to too many files.
    warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
    [xsa349_4.9 10d6c1301412] xen/xenbus/xen_bus_type: Support will_handle watch callback
     Date: Mon Dec 14 10:05:47 2020 +0100
     2 files changed, 4 insertions(+), 1 deletion(-)
    warning: inexact rename detection was skipped due to too many files.
    warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
    [xsa349_4.9 3875703f1e6b] xen/xenbus: Count pending messages for each watch
     Date: Mon Dec 14 10:07:13 2020 +0100
     2 files changed, 21 insertions(+), 12 deletions(-)
    warning: inexact rename detection was skipped due to too many files.
    warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
    [xsa349_4.9 40e3b315cd18] xenbus/xenbus_backend: Disallow pending watch messages
     Date: Mon Dec 14 10:08:40 2020 +0100
     1 file changed, 7 insertions(+)

Seems you tried to merge the series for upstream in 4.9.y:

    https://lore.kernel.org/stable/1609154834239118@kroah.com/

This must because I didn't test this series with v4.9 and mention it.  Sorry
for making a confusion.  Could you please check this again?


Thanks,
SeongJae Park

Re: [PATCH v3 0/5] Backport of patch series for stable 4.4 branch

[Greg KH]

On Tue, Jan 05, 2021 at 11:37:02AM +0100, SeongJae Park wrote:
> Hi Greg,
> 
> On Mon, 28 Dec 2020 12:29:11 +0100 Greg KH <gregkh@linuxfoundation.org> wrote:
> 
> > On Thu, Dec 17, 2020 at 05:03:57PM +0100, SeongJae Park wrote:
> > > From: SeongJae Park <sjpark@amazon.de>
> > > 
> > > Changes from v2
> > > (https://lore.kernel.org/stable/20201217130501.12702-1-sjpark@amazon.com/)
> > > - Move 'nr_pending' increase from 5th patch to 4th patch
> > > 
> > > Changes from v1
> > > (https://lore.kernel.org/stable/20201217081727.8253-1-sjpark@amazon.com/)
> > > - Remove wrong 'Signed-off-by' lines for 'Author Redacted'
> > 
> > All now queued up, but you also need a series of this for the 4.9.y tree
> > as well.
> 
> Thank you for your efforts!
> 
> However, I was able to cherry-pick this series, which is already merged in
> 4.4.y, to 4.9.y without conflicts.
> 
>     $ git checkout stable/linux-4.9.y -b xsa349_4.9
>     $ git cherry-pick d8b0d52e408ca..3c71d2f637c8
>     warning: inexact rename detection was skipped due to too many files.
>     warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
>     [xsa349_4.9 51b4cb3db28a] xen/xenbus: Allow watches discard events before queueing
>      Date: Mon Dec 14 10:02:45 2020 +0100
>      4 files changed, 16 insertions(+), 1 deletion(-)
>     warning: inexact rename detection was skipped due to too many files.
>     warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
>     [xsa349_4.9 3242225d9645] xen/xenbus: Add 'will_handle' callback support in xenbus_watch_path()
>      Date: Mon Dec 14 10:04:18 2020 +0100
>      6 files changed, 17 insertions(+), 7 deletions(-)
>     warning: inexact rename detection was skipped due to too many files.
>     warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
>     [xsa349_4.9 10d6c1301412] xen/xenbus/xen_bus_type: Support will_handle watch callback
>      Date: Mon Dec 14 10:05:47 2020 +0100
>      2 files changed, 4 insertions(+), 1 deletion(-)
>     warning: inexact rename detection was skipped due to too many files.
>     warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
>     [xsa349_4.9 3875703f1e6b] xen/xenbus: Count pending messages for each watch
>      Date: Mon Dec 14 10:07:13 2020 +0100
>      2 files changed, 21 insertions(+), 12 deletions(-)
>     warning: inexact rename detection was skipped due to too many files.
>     warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
>     [xsa349_4.9 40e3b315cd18] xenbus/xenbus_backend: Disallow pending watch messages
>      Date: Mon Dec 14 10:08:40 2020 +0100
>      1 file changed, 7 insertions(+)
> 
> Seems you tried to merge the series for upstream in 4.9.y:
> 
>     https://lore.kernel.org/stable/1609154834239118@kroah.com/
> 
> This must because I didn't test this series with v4.9 and mention it.  Sorry
> for making a confusion.  Could you please check this again?

I can't do anything with a set of git cherry-picks like above, can you
please send the patches as a series so that I can apply them cleanly?

And I don't remember what happened with that failure, sorry, dealing
with hundreds of patches a week makes them all blur together...

thanks,

greg k-h

Re: [PATCH v3 0/5] Backport of patch series for stable 4.4 branch

[SeongJae Park]

On Tue, 5 Jan 2021 11:43:42 +0100 Greg KH <gregkh@linuxfoundation.org> wrote:

> On Tue, Jan 05, 2021 at 11:37:02AM +0100, SeongJae Park wrote:
> > Hi Greg,
> > 
> > On Mon, 28 Dec 2020 12:29:11 +0100 Greg KH <gregkh@linuxfoundation.org> wrote:
> > 
> > > On Thu, Dec 17, 2020 at 05:03:57PM +0100, SeongJae Park wrote:
> > > > From: SeongJae Park <sjpark@amazon.de>
> > > > 
> > > > Changes from v2
> > > > (https://lore.kernel.org/stable/20201217130501.12702-1-sjpark@amazon.com/)
> > > > - Move 'nr_pending' increase from 5th patch to 4th patch
> > > > 
> > > > Changes from v1
> > > > (https://lore.kernel.org/stable/20201217081727.8253-1-sjpark@amazon.com/)
> > > > - Remove wrong 'Signed-off-by' lines for 'Author Redacted'
> > > 
> > > All now queued up, but you also need a series of this for the 4.9.y tree
> > > as well.
> > 
> > Thank you for your efforts!
> > 
> > However, I was able to cherry-pick this series, which is already merged in
> > 4.4.y, to 4.9.y without conflicts.
> > 
> >     $ git checkout stable/linux-4.9.y -b xsa349_4.9
> >     $ git cherry-pick d8b0d52e408ca..3c71d2f637c8
> >     warning: inexact rename detection was skipped due to too many files.
> >     warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
> >     [xsa349_4.9 51b4cb3db28a] xen/xenbus: Allow watches discard events before queueing
> >      Date: Mon Dec 14 10:02:45 2020 +0100
> >      4 files changed, 16 insertions(+), 1 deletion(-)
> >     warning: inexact rename detection was skipped due to too many files.
> >     warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
> >     [xsa349_4.9 3242225d9645] xen/xenbus: Add 'will_handle' callback support in xenbus_watch_path()
> >      Date: Mon Dec 14 10:04:18 2020 +0100
> >      6 files changed, 17 insertions(+), 7 deletions(-)
> >     warning: inexact rename detection was skipped due to too many files.
> >     warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
> >     [xsa349_4.9 10d6c1301412] xen/xenbus/xen_bus_type: Support will_handle watch callback
> >      Date: Mon Dec 14 10:05:47 2020 +0100
> >      2 files changed, 4 insertions(+), 1 deletion(-)
> >     warning: inexact rename detection was skipped due to too many files.
> >     warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
> >     [xsa349_4.9 3875703f1e6b] xen/xenbus: Count pending messages for each watch
> >      Date: Mon Dec 14 10:07:13 2020 +0100
> >      2 files changed, 21 insertions(+), 12 deletions(-)
> >     warning: inexact rename detection was skipped due to too many files.
> >     warning: you may want to set your merge.renamelimit variable to at least 6130 and retry the command.
> >     [xsa349_4.9 40e3b315cd18] xenbus/xenbus_backend: Disallow pending watch messages
> >      Date: Mon Dec 14 10:08:40 2020 +0100
> >      1 file changed, 7 insertions(+)
> > 
> > Seems you tried to merge the series for upstream in 4.9.y:
> > 
> >     https://lore.kernel.org/stable/1609154834239118@kroah.com/
> > 
> > This must because I didn't test this series with v4.9 and mention it.  Sorry
> > for making a confusion.  Could you please check this again?
> 
> I can't do anything with a set of git cherry-picks like above, can you
> please send the patches as a series so that I can apply them cleanly?

Sure, I will post it soon.

> 
> And I don't remember what happened with that failure, sorry, dealing
> with hundreds of patches a week makes them all blur together...

I understand.  No problem at all.


Thanks,
SeongJae Park