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[bug #54739] "alloc magic is broken" on NVME SSD

From: Magnus Lucchese
Subject: [bug #54739] "alloc magic is broken" on NVME SSD
Date: Wed, 26 Sep 2018 20:50:33 -0400 (EDT)
User-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36


                 Summary: "alloc magic is broken" on NVME SSD
                 Project: GNU GRUB
            Submitted by: maglu
            Submitted on: Thu 27 Sep 2018 12:50:31 AM UTC
                Category: Booting
                Severity: Major
                Priority: 5 - Normal
              Item Group: Software Error
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 2.02
         Reproducibility: Every Time
         Planned Release: None



I have a server with multiple NVME SSDs, I noticed that after some tests on
these SSDs I got the error below when rebooting (the address change on each

*alloc magic is broken at 0x34e79f00: ffffffffffffffff*

(see full log attached)

The SSD that cause the fail is not the one were GRUB/Linux are installed, when
I remove it the system boots correctly.

== Some things that I found during debug ==

 * This SSD format is 4KB + 16 Bytes of metadata, metadata is interleaved with
the LBA (NVME Metadata Capabilities (MC))
 * The SSD is completely erased (return all 1's).
 * The maximum allowed size for reads on this SSD is 128KB (NVME MDTS
 * GRUB is trying to perform some reads greater than 128KB and receives an
error from the SSD ("Invalid Field Error").
 * If I change the SSD format to 4KB+0 GRUB works properly and don't issue any
reader greater than the maximum size.
== My Suspicions == 

 I think that when GRUB calculate the maximum size it can read it is not
considering metadata interleaved. The reads that extrapolate the maximum size
overflow by the amount of metadata, besides that, it seems that it is not
handling the error received from the SSD.

== Versions Tested ==



File Attachments:

Date: Thu 27 Sep 2018 12:50:31 AM UTC  Name: grub_error_report.txt  Size:
35KiB   By: maglu



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