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[ Upstream commit 6bd23e0c2bb6c65d4f5754d1456bc9a4427fc59b ] ... and use it to limit the virtual terminals to just N_TTY. They are kind of special, and in particular, the "con_write()" routine violates the "writes cannot sleep" rule that some ldiscs rely on. This avoids the BUG: sleeping function called from invalid context at kernel/printk/printk.c:2659 when N_GSM has been attached to a virtual console, and gsmld_write() calls con_write() while holding a spinlock, and con_write() then tries to get the console lock. Tested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Daniel Starke <daniel.starke@siemens.com> Reported-by: syzbot <syzbot+dbac96d8e73b61aa559c@syzkaller.appspotmail.com> Closes: https://syzkaller.appspot.com/bug?extid=dbac96d8e73b61aa559c Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20240423163339.59780-1-torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.