linux-kernel - Re: [PATCH][CFT] [coredump] don't use __kernel_write() on kmap_local

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Date:   Mon, 03 Oct 2022 19:48:28 +0900
From:   "J. R. Okajima" <hooanon05g@...il.com>
To:     Ira Weiny <ira.weiny@...el.com>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH][CFT] [coredump] don't use __kernel_write() on kmap_local_page()

Ira Weiny:
> On Wed, Sep 28, 2022 at 07:29:43PM +0100, Al Viro wrote:
> > On Tue, Sep 27, 2022 at 11:51:17PM +0100, Al Viro wrote:
> > > [I'm going to send a pull request tomorrow if nobody yells;
> > > please review and test - it seems to work fine here, but extra
> > > eyes and extra testing would be very welcome]

I tried gdb backtrace 'bt' command with the new core by v6.0, and it
doesn't show the call trace correctly. Is it related to this commit?

test program
----------------------------------------
void f(int n)
{
	printf("%d\n", n);
	if (!n)
		kill(getpid(), SIGQUIT);
	f(--n);
}

int main(int argc, char *argv[])
{
	f(atoi(argv[1]));
	return 0;
}
----------------------------------------
ulimit -c unlimited
coredump 2
gdb coredump core
bt
----------------------------------------
expected result
kill
f
f
f
main
----------------------------------------
actual result
??
??
----------------------------------------


J. R. Okajima