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Date:   Thu, 13 Jun 2019 15:00:19 +0200 (CEST)
From:   Miroslav Benes <mbenes@suse.cz>
To:     Joe Lawrence <joe.lawrence@redhat.com>
cc:     linux-kernel@vger.kernel.org, live-patching@vger.kernel.org,
        linux-kbuild@vger.kernel.org
Subject: Re: [PATCH v4 00/10] klp-convert livepatch build tooling
In-Reply-To: <20190509143859.9050-1-joe.lawrence@redhat.com>
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References: <20190509143859.9050-1-joe.lawrence@redhat.com>
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Hi Joe,

first, I'm sorry for the lack of response so far.

Maybe you've already noticed but the selftests fail. Well, at least in 
my VM. When test_klp_convert1.ko is loaded, the process is killed with

[  518.041826] BUG: kernel NULL pointer dereference, address: 0000000000000000
[  518.042816] #PF: supervisor read access in kernel mode
[  518.043393] #PF: error_code(0x0000) - not-present page
[  518.043981] PGD 0 P4D 0 
[  518.044185] Oops: 0000 [#1] SMP PTI
[  518.044518] CPU: 2 PID: 2255 Comm: insmod Tainted: G           O  K   5.1.0-klp_convert_v4-193435-g67748576637e #2
[  518.045784] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58-prebuilt.qemu.org 04/01/2014
[  518.046940] RIP: 0010:test_klp_convert_init+0x1c/0x40 [test_klp_convert1]
[  518.047611] Code: 1b a0 48 89 c6 e9 a8 c0 f4 e0 0f 1f 40 00 0f 1f 44 00 00 53 48 c7 c7 00 30 1b a0 e8 5e 33 f6 e0 85 c0 89 c3 74 04 89 d8 5b c3 <48> 8b 35 5d ef e4 5f 48 c7 c7 28 20 1b a0 e8 75 c0 f4 e0 e8 6c ff
[  518.049779] RSP: 0018:ffffc90000f37cc8 EFLAGS: 00010246
[  518.050243] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000027de0
[  518.050922] RDX: 0000000000000000 RSI: 0000000000000006 RDI: ffff88807ab54f40
[  518.051619] RBP: ffffffffa01b1080 R08: 0000000096efde7a R09: 0000000000000001
[  518.052332] R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff
[  518.053012] R13: 0000000000000000 R14: ffff888078b55000 R15: ffffc90000f37ea0
[  518.053714] FS:  00007febece1fb80(0000) GS:ffff88807d400000(0000) knlGS:0000000000000000
[  518.054514] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  518.055078] CR2: 0000000000000000 CR3: 000000007a56a000 CR4: 00000000000006e0
[  518.055818] Call Trace:
[  518.056007]  do_one_initcall+0x6a/0x2da
[  518.056340]  ? do_init_module+0x22/0x230
[  518.056702]  ? rcu_read_lock_sched_held+0x96/0xa0
[  518.057125]  ? kmem_cache_alloc_trace+0x284/0x2e0
[  518.057493]  do_init_module+0x5a/0x230
[  518.057900]  load_module+0x17bc/0x1f50
[  518.058214]  ? __symbol_put+0x40/0x40
[  518.058499]  ? vfs_read+0x12d/0x160
[  518.058766]  __do_sys_finit_module+0x83/0xc0
[  518.059122]  do_syscall_64+0x57/0x190
[  518.059407]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
...

It crashes right in test_klp_convert_init() when print_*() using 
supposed-to-be-converted symbols are called. I'll debug it next week. Can 
you reproduce it too?

Regards,
Miroslav

PS: it is probably not a coincidence that I come across selftests failures 
right before I leave for a holiday...