https://bugs.chromium.org/p/chromium/issues/detail?id=761579#c14

points at code/conditions that might lead to kernel crashes not getting reported because the ramoops file wasn't created.

The goal is, if crash reporting is enabled by the user, we should _always_ report _something_ if we can detect any semi-valid contents in the dmesg buffer.

I think the only area we can NOT report crashes is if something causes power to fail - since the reboot will look exactly like a cold start. E.g. EC shutdowns will likely not get reported ever.
1) kernel should either create a different file OR be more lenient in creating the ramoops file should some part of the kmsg header be corrupted. See ~/trunk/src/third_party/kernel/v4.4/fs/pstore/ram.c :

262                 header_length = ramoops_read_kmsg_hdr(persistent_ram_old(prz),
263                                                       &record->time,
264                                                       &record->compressed);
265                 /* Clear and skip this DMESG record if it has no valid header */
266                 if (!header_length) {
267                         persistent_ram_free_old(prz);
268                         persistent_ram_zap(prz);
269                         prz = NULL;
270                 }


2) kernel_collector.cc needs to look for and possibly handle these potentially corrupted kernel crash dumps carefully.


153 bool KernelCollector::LoadParameters() {
154   // Discover how many ramoops records are being exported by the driver.
155   size_t count;
156 
157   for (count = 0; count < kMaxDumpRecords; ++count) {
158     FilePath record_path = GetDumpRecordPath(kDumpRecordDmesgName,
159                                              kDumpDriverRamoopsName, count);
160 
161     if (!base::PathExists(record_path))
162       break;
163   }
164 
165   records_ = count;
166   return (records_ > 0);
167 }

or if the stripped message buffer has no contents, then we don't report it either:

609   StripSensitiveData(&kernel_dump);
610   if (kernel_dump.empty()) {
611     return false;
612   }

We should report something in both cases.