[PATCH RT 0/3] Linux v5.10.180-rt89-rc1

[PATCH RT 0/3] Linux v5.10.180-rt89-rc1

[Luis Claudio R. Goncalves]

Dear RT Folks,

This is the RT stable review cycle of patch 5.10.180-rt89-rc1.

Please scream at me if I messed something up. Please test the patches
too.

The -rc release will be uploaded to kernel.org and will be deleted
when the final release is out. This is just a review release (or
release candidate).

The pre-releases will not be pushed to the git repository, only the
final release is.

If all goes well, this patch will be converted to the next main
release on 2023-06-15.

To build 5.10.180-rt89-rc1 directly, the following patches should be applied:

  https://www.kernel.org/pub/linux/kernel/v5.x/linux-5.10.tar.xz

  https://www.kernel.org/pub/linux/kernel/v5.x/patch-5.10.180.xz

  https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patch-5.10.180-rt89-rc1.patch.xz

Signing key fingerprint:

  4FDD B8C4 3C59 34BD 8BE9  2696 7203 D980 A448 C8F8

All keys used for the above files and repositories can be found on the
following git repository:

   git://git.kernel.org/pub/scm/docs/kernel/pgpkeys.git

Enjoy!
Luis

Changes from v5.10.180-rt88:


Luis Claudio R. Goncalves (3):
  Revert "printk: declare printk_deferred_{enter,safe}() in
    include/linux/printk.h"
  Revert "mm/page_alloc: fix potential deadlock on
    zonelist_update_seqseqlock"
  Linux 5.10.180-rt89-rc1

 include/linux/printk.h | 19 -------------------
 localversion-rt        |  2 +-
 mm/page_alloc.c        | 14 --------------
 3 files changed, 1 insertion(+), 34 deletions(-)

-- 
2.40.1

[PATCH RT 1/3] Revert "printk: declare printk_deferred_{enter,safe}() in include/linux/printk.h"

[Luis Claudio R. Goncalves]

v5.10.180-rt89-rc1 stable review patch.
If anyone has any objections, please let me know.

-----------


This reverts commit 32232bcd4e5300e678718d5c29da4dfa07ade01e.

The support for deferred printing was removed in v5.10-rc1-rt1 by commit
9153e3c5cb0c9 ("printk: remove deferred printing") because:

    Since printing occurs either atomically or from the printing
    kthread, there is no need for any deferring or tracking possible
    recursion paths. Remove all printk context tracking.

Fixes: 32232bcd4e530 ("printk: declare printk_deferred_{enter,safe}() in include/linux/printk.h")
Fixes: 083183f8bea0f ("rt: printk: remove new references to deferred printing")
Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
---
 include/linux/printk.h | 19 -------------------
 1 file changed, 19 deletions(-)

diff --git a/include/linux/printk.h b/include/linux/printk.h
index 92e0656841128..7e4352467d831 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -609,23 +609,4 @@ static inline void print_hex_dump_debug(const char *prefix_str, int prefix_type,
 #define print_hex_dump_bytes(prefix_str, prefix_type, buf, len)	\
 	print_hex_dump_debug(prefix_str, prefix_type, 16, 1, buf, len, true)
 
-#if defined(CONFIG_PRINTK) && !defined(CONFIG_PREEMPT_RT)
-extern void __printk_safe_enter(void);
-extern void __printk_safe_exit(void);
-/*
- * The printk_deferred_enter/exit macros are available only as a hack for
- * some code paths that need to defer all printk console printing. Interrupts
- * must be disabled for the deferred duration.
- */
-#define printk_deferred_enter __printk_safe_enter
-#define printk_deferred_exit __printk_safe_exit
-#else /* defined(CONFIG_PRINTK) && !defined(CONFIG_PREEMPT_RT) */
-static inline void printk_deferred_enter(void)
-{
-}
-static inline void printk_deferred_exit(void)
-{
-}
-#endif
-
 #endif
-- 
2.40.1

[PATCH RT 2/3] Revert "mm/page_alloc: fix potential deadlock on zonelist_update_seqseqlock"

[Luis Claudio R. Goncalves]

v5.10.180-rt89-rc1 stable review patch.
If anyone has any objections, please let me know.

-----------


This reverts commit a992c387b41186ab968fd176ca26b432b05c53ec.

The support for deferred printing was removed in v5.10-rc1-rt1 by commit
9153e3c5cb0c9 ("printk: remove deferred printing") because:

    Since printing occurs either atomically or from the printing
    kthread, there is no need for any deferring or tracking possible
    recursion paths. Remove all printk context tracking.

Also, disabling interrupts in __build_all_zonelists() should produce warnings
once that code path is hit.

Fixes: a992c387b4118 ("mm/page_alloc: fix potential deadlock on zonelist_update_seq seqlock")
Fixes: 083183f8bea0f ("rt: printk: remove new references to deferred printing")
Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
---
 mm/page_alloc.c | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7e65e3ef16e3a..3760a06932a6e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6043,20 +6043,7 @@ static void __build_all_zonelists(void *data)
 	int nid;
 	int __maybe_unused cpu;
 	pg_data_t *self = data;
-	unsigned long flags;
 
-	/*
-	 * Explicitly disable this CPU's interrupts before taking seqlock
-	 * to prevent any IRQ handler from calling into the page allocator
-	 * (e.g. GFP_ATOMIC) that could hit zonelist_iter_begin and livelock.
-	 */
-	local_irq_save(flags);
-	/*
-	 * Explicitly disable this CPU's synchronous printk() before taking
-	 * seqlock to prevent any printk() from trying to hold port->lock, for
-	 * tty_insert_flip_string_and_push_buffer() on other CPU might be
-	 * calling kmalloc(GFP_ATOMIC | __GFP_NOWARN) with port->lock held.
-	 */
 	write_seqlock(&zonelist_update_seq);
 
 #ifdef CONFIG_NUMA
@@ -6091,7 +6078,6 @@ static void __build_all_zonelists(void *data)
 	}
 
 	write_sequnlock(&zonelist_update_seq);
-	local_irq_restore(flags);
 }
 
 static noinline void __init
-- 
2.40.1

[PATCH RT 3/3] Linux 5.10.180-rt89-rc1

[Luis Claudio R. Goncalves]

v5.10.180-rt89-rc1 stable review patch.
If anyone has any objections, please let me know.

-----------


Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
---
 localversion-rt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/localversion-rt b/localversion-rt
index 666227d921a3d..d1173dc87024f 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt88
+-rt89-rc1
-- 
2.40.1

Re: [PATCH RT 3/3] Linux 5.10.180-rt89-rc1

[Sebastian Andrzej Siewior]

On 2023-06-08 22:11:04 [-0300], Luis Claudio R. Goncalves wrote:
> v5.10.180-rt89-rc1 stable review patch.
> If anyone has any objections, please let me know.

Thank you, this looks good. Looking at it again made realize that I need
something like 2/3 in my tree, too.

Sebastian