[merged] seq_buf-add-seq_buf_do_printk-helper.patch removed from -mm tree

[merged] seq_buf-add-seq_buf_do_printk-helper.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: seq_buf: add seq_buf_do_printk() helper
has been removed from the -mm tree.  Its filename was
     seq_buf-add-seq_buf_do_printk-helper.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@chromium.org>
Subject: seq_buf: add seq_buf_do_printk() helper
Date: Sat, 15 Apr 2023 19:01:10 +0900

(akpm: temporary addition for
memcg-use-seq_buf_do_printk-with-mem_cgroup_print_oom_meminfo.patch)

Sometimes we use seq_buf to format a string buffer, which we then pass to
printk().  However, in certain situations the seq_buf string buffer can
get too big, exceeding the PRINTKRB_RECORD_MAX bytes limit, and causing
printk() to truncate the string.

Add a new seq_buf helper.  This helper prints the seq_buf string buffer
line by line, using as a delimiter, rather than passing the whole string
buffer to printk() at once.

Link: https://lkml.kernel.org/r/20230415100110.1419872-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/seq_buf.h |    2 ++
 lib/seq_buf.c           |   32 ++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

--- a/include/linux/seq_buf.h~seq_buf-add-seq_buf_do_printk-helper
+++ a/include/linux/seq_buf.h
@@ -159,4 +159,6 @@ extern int
 seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary);
 #endif
 
+void seq_buf_do_printk(struct seq_buf *s, const char *lvl);
+
 #endif /* _LINUX_SEQ_BUF_H */
--- a/lib/seq_buf.c~seq_buf-add-seq_buf_do_printk-helper
+++ a/lib/seq_buf.c
@@ -93,6 +93,38 @@ int seq_buf_printf(struct seq_buf *s, co
 }
 EXPORT_SYMBOL_GPL(seq_buf_printf);
 
+/**
+ * seq_buf_do_printk - printk seq_buf line by line
+ * @s: seq_buf descriptor
+ * @lvl: printk level
+ *
+ * printk()-s a multi-line sequential buffer line by line. The function
+ * makes sure that the buffer in @s is nul terminated and safe to read
+ * as a string.
+ */
+void seq_buf_do_printk(struct seq_buf *s, const char *lvl)
+{
+	const char *start, *lf;
+
+	if (s->size == 0 || s->len == 0)
+		return;
+
+	seq_buf_terminate(s);
+
+	start = s->buffer;
+	while ((lf = strchr(start, '\n'))) {
+		int len = lf - start + 1;
+
+		printk("%s%.*s", lvl, len, start);
+		start = ++lf;
+	}
+
+	/* No trailing LF */
+	if (start < s->buffer + s->len)
+		printk("%s%s\n", lvl, start);
+}
+EXPORT_SYMBOL_GPL(seq_buf_do_printk);
+
 #ifdef CONFIG_BINARY_PRINTF
 /**
  * seq_buf_bprintf - Write the printf string from binary arguments
_

Patches currently in -mm which might be from senozhatsky@chromium.org are

Re: [merged] seq_buf-add-seq_buf_do_printk-helper.patch removed from -mm tree

[SeongJae Park]

Hi Andrew,

On Fri, 05 May 2023 15:45:21 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:

> 
> The quilt patch titled
>      Subject: seq_buf: add seq_buf_do_printk() helper
> has been removed from the -mm tree.  Its filename was
>      seq_buf-add-seq_buf_do_printk-helper.patch
> 
> This patch was dropped because it was merged into mainline or a subsystem tree

Just for headup.  I just found the latest mm-unstable indeed dropped the patch
but a patch[1] depends on it.  As a result, build fails as below.

      CC      mm/memcontrol.o
    /mm/memcontrol.c: In function ‘mem_cgroup_print_oom_meminfo’:
    /mm/memcontrol.c:1693:2: error: implicit declaration of function ‘seq_buf_do_printk’; did you mean ‘seq_buf_bprintf’? [-Werror=implicit-function-declaration]
     1693 |  seq_buf_do_printk(&s, KERN_INFO);
          |  ^~~~~~~~~~~~~~~~~
          |  seq_buf_bprintf
    cc1: some warnings being treated as errors

[1] https://lore.kernel.org/mm-commits/20230502201509.B8711C433D2@smtp.kernel.org/


Thanks,
SJ

> 
> ------------------------------------------------------
> From: Sergey Senozhatsky <senozhatsky@chromium.org>
> Subject: seq_buf: add seq_buf_do_printk() helper
> Date: Sat, 15 Apr 2023 19:01:10 +0900
> 
> (akpm: temporary addition for
> memcg-use-seq_buf_do_printk-with-mem_cgroup_print_oom_meminfo.patch)
> 
> Sometimes we use seq_buf to format a string buffer, which we then pass to
> printk().  However, in certain situations the seq_buf string buffer can
> get too big, exceeding the PRINTKRB_RECORD_MAX bytes limit, and causing
> printk() to truncate the string.
> 
> Add a new seq_buf helper.  This helper prints the seq_buf string buffer
> line by line, using as a delimiter, rather than passing the whole string
> buffer to printk() at once.
> 
> Link: https://lkml.kernel.org/r/20230415100110.1419872-1-senozhatsky@chromium.org
> Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> Reviewed-by: Petr Mladek <pmladek@suse.com>
> Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
> Cc: Yosry Ahmed <yosryahmed@google.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Re: [merged] seq_buf-add-seq_buf_do_printk-helper.patch removed from -mm tree

[Yosry Ahmed]

On Fri, May 5, 2023 at 4:57 PM SeongJae Park <sj@kernel.org> wrote:
>
> Hi Andrew,
>
> On Fri, 05 May 2023 15:45:21 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:
>
> >
> > The quilt patch titled
> >      Subject: seq_buf: add seq_buf_do_printk() helper
> > has been removed from the -mm tree.  Its filename was
> >      seq_buf-add-seq_buf_do_printk-helper.patch
> >
> > This patch was dropped because it was merged into mainline or a subsystem tree
>
> Just for headup.  I just found the latest mm-unstable indeed dropped the patch
> but a patch[1] depends on it.  As a result, build fails as below.

That patch was merged into Linus's tree, so I assumed that's why it
was dropped from mm-unstable. Perhaps I am wrong.

>
>       CC      mm/memcontrol.o
>     /mm/memcontrol.c: In function ‘mem_cgroup_print_oom_meminfo’:
>     /mm/memcontrol.c:1693:2: error: implicit declaration of function ‘seq_buf_do_printk’; did you mean ‘seq_buf_bprintf’? [-Werror=implicit-function-declaration]
>      1693 |  seq_buf_do_printk(&s, KERN_INFO);
>           |  ^~~~~~~~~~~~~~~~~
>           |  seq_buf_bprintf
>     cc1: some warnings being treated as errors
>
> [1] https://lore.kernel.org/mm-commits/20230502201509.B8711C433D2@smtp.kernel.org/
>
>
> Thanks,
> SJ
>
> >
> > ------------------------------------------------------
> > From: Sergey Senozhatsky <senozhatsky@chromium.org>
> > Subject: seq_buf: add seq_buf_do_printk() helper
> > Date: Sat, 15 Apr 2023 19:01:10 +0900
> >
> > (akpm: temporary addition for
> > memcg-use-seq_buf_do_printk-with-mem_cgroup_print_oom_meminfo.patch)
> >
> > Sometimes we use seq_buf to format a string buffer, which we then pass to
> > printk().  However, in certain situations the seq_buf string buffer can
> > get too big, exceeding the PRINTKRB_RECORD_MAX bytes limit, and causing
> > printk() to truncate the string.
> >
> > Add a new seq_buf helper.  This helper prints the seq_buf string buffer
> > line by line, using as a delimiter, rather than passing the whole string
> > buffer to printk() at once.
> >
> > Link: https://lkml.kernel.org/r/20230415100110.1419872-1-senozhatsky@chromium.org
> > Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> > Reviewed-by: Petr Mladek <pmladek@suse.com>
> > Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
> > Cc: Yosry Ahmed <yosryahmed@google.com>
> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Re: [merged] seq_buf-add-seq_buf_do_printk-helper.patch removed from -mm tree

[SeongJae Park]

On Fri, 5 May 2023 17:00:20 -0700 Yosry Ahmed <yosryahmed@google.com> wrote:

> On Fri, May 5, 2023 at 4:57 PM SeongJae Park <sj@kernel.org> wrote:
> >
> > Hi Andrew,
> >
> > On Fri, 05 May 2023 15:45:21 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:
> >
> > >
> > > The quilt patch titled
> > >      Subject: seq_buf: add seq_buf_do_printk() helper
> > > has been removed from the -mm tree.  Its filename was
> > >      seq_buf-add-seq_buf_do_printk-helper.patch
> > >
> > > This patch was dropped because it was merged into mainline or a subsystem tree
> >
> > Just for headup.  I just found the latest mm-unstable indeed dropped the patch
> > but a patch[1] depends on it.  As a result, build fails as below.
> 
> That patch was merged into Linus's tree, so I assumed that's why it
> was dropped from mm-unstable. Perhaps I am wrong.

Same to my assumption, and fit with the original mail's explanation.  I
confirmed the patch has merged in the mainline as commit 96928d9032a7.  So this
will be fixed if 1) mm-unstable is rebased on v6.4-rc1, 2) the dropped patch is
added again on mm-unstable, or 3) the patch[1] currently triggering the failure
is dropped.  This is never an important issue for me, so I don't have any
preference or opinion about the fix.  I just wanted to save time for others who
might got report of this.

[1] https://lore.kernel.org/mm-commits/20230502201509.B8711C433D2@smtp.kernel.org/


Thanks,
SJ

> 
> >
> >       CC      mm/memcontrol.o
> >     /mm/memcontrol.c: In function ‘mem_cgroup_print_oom_meminfo’:
> >     /mm/memcontrol.c:1693:2: error: implicit declaration of function ‘seq_buf_do_printk’; did you mean ‘seq_buf_bprintf’? [-Werror=implicit-function-declaration]
> >      1693 |  seq_buf_do_printk(&s, KERN_INFO);
> >           |  ^~~~~~~~~~~~~~~~~
> >           |  seq_buf_bprintf
> >     cc1: some warnings being treated as errors
> >
> > [1] https://lore.kernel.org/mm-commits/20230502201509.B8711C433D2@smtp.kernel.org/
> >
> >
> > Thanks,
> > SJ

Re: [merged] seq_buf-add-seq_buf_do_printk-helper.patch removed from -mm tree

[Andrew Morton]

On Sat,  6 May 2023 00:28:05 +0000 SeongJae Park <sj@kernel.org> wrote:

> > That patch was merged into Linus's tree, so I assumed that's why it
> > was dropped from mm-unstable. Perhaps I am wrong.
> 
> Same to my assumption, and fit with the original mail's explanation.  I
> confirmed the patch has merged in the mainline as commit 96928d9032a7.  So this
> will be fixed if 1) mm-unstable is rebased on v6.4-rc1, 2) the dropped patch is
> added again on mm-unstable, or 3) the patch[1] currently triggering the failure
> is dropped.  This is never an important issue for me, so I don't have any
> preference or opinion about the fix.  I just wanted to save time for others who
> might got report of this.

The mm-everything which I just pushed out has seq_buf_do_printk().

The mm-unstable branch doesn't, oops.  I'll fix and repush.