Re: Crash in msm serial on dragonboard with ftrace bootargs

From: Sai Prakash Ranjan
Date: Wed Oct 17 2018 - 10:50:08 EST

On 10/17/2018 5:08 PM, Sai Prakash Ranjan wrote:

What do you think about the (untested) patch below? It seems to me that it
should solve the issue of missing early crash dumps, but I have not tested it
yet. Sai, would you mind trying it out and let me know if you can see the
early crash dumps properly now?

From: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx>
Subject: [RFC] pstore: allocate compression during late_initcall

ramoop's pstore registration (using pstore_register) has to run during
late_initcall because crypto backend may not be ready during
postcore_initcall. This causes missing of dmesg crash dumps which could
have been caught by pstore.

Instead, lets allow ramoops pstore registration earlier, and once crypto
is ready we can initialize the compression.

Reported-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
 fs/pstore/platform.c | 13 +++++++++++++
 fs/pstore/ram.c | 2 +-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 15e99d5a681d..f09066db2d4d 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -780,6 +780,19 @@ void __init pstore_choose_compression(void)
+static int __init pstore_compression_late_init(void)
+ÂÂÂ /*
+ÂÂÂÂ * Check if any pstore backends registered earlier but did not allocate
+ÂÂÂÂ * for compression because crypto was not ready, if so then initialize
+ÂÂÂÂ * compression.
+ÂÂÂÂ */
+ÂÂÂ if (psinfo && !tfm)
+ÂÂÂÂÂÂÂ allocate_buf_for_compression();
+ÂÂÂ return 0;
 module_param(compress, charp, 0444);
 MODULE_PARM_DESC(compress, "Pstore compression to use");
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index bbd1e357c23d..98e48d1a9776 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -940,7 +940,7 @@ static int __init ramoops_init(void)
ÂÂÂÂÂ ramoops_register_dummy();
ÂÂÂÂÂ return platform_driver_register(&ramoops_driver);
 static void __exit ramoops_exit(void)

Yes I could see the early crash dump. Also I tested with different compression (LZO) instead of deflate just to be sure and it works fine, thanks :)

Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>

I just noticed that allocate_buf_for_compression() is also called from pstore_register(). Shouldn't that call be removed now that ramoops_init is moved to postcore_initcall and allocate_buf_for_compression() will just return doing nothing when called from pstore_register()?


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