lkml.org 
[lkml]   [2019]   [Jul]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH AUTOSEL 4.14 06/37] kernel/module.c: Only return -EEXIST for modules that have finished loading
    Date
    From: Prarit Bhargava <prarit@redhat.com>

    [ Upstream commit 6e6de3dee51a439f76eb73c22ae2ffd2c9384712 ]

    Microsoft HyperV disables the X86_FEATURE_SMCA bit on AMD systems, and
    linux guests boot with repeated errors:

    amd64_edac_mod: Unknown symbol amd_unregister_ecc_decoder (err -2)
    amd64_edac_mod: Unknown symbol amd_register_ecc_decoder (err -2)
    amd64_edac_mod: Unknown symbol amd_report_gart_errors (err -2)
    amd64_edac_mod: Unknown symbol amd_unregister_ecc_decoder (err -2)
    amd64_edac_mod: Unknown symbol amd_register_ecc_decoder (err -2)
    amd64_edac_mod: Unknown symbol amd_report_gart_errors (err -2)

    The warnings occur because the module code erroneously returns -EEXIST
    for modules that have failed to load and are in the process of being
    removed from the module list.

    module amd64_edac_mod has a dependency on module edac_mce_amd. Using
    modules.dep, systemd will load edac_mce_amd for every request of
    amd64_edac_mod. When the edac_mce_amd module loads, the module has
    state MODULE_STATE_UNFORMED and once the module load fails and the state
    becomes MODULE_STATE_GOING. Another request for edac_mce_amd module
    executes and add_unformed_module() will erroneously return -EEXIST even
    though the previous instance of edac_mce_amd has MODULE_STATE_GOING.
    Upon receiving -EEXIST, systemd attempts to load amd64_edac_mod, which
    fails because of unknown symbols from edac_mce_amd.

    add_unformed_module() must wait to return for any case other than
    MODULE_STATE_LIVE to prevent a race between multiple loads of
    dependent modules.

    Signed-off-by: Prarit Bhargava <prarit@redhat.com>
    Signed-off-by: Barret Rhoden <brho@google.com>
    Cc: David Arcari <darcari@redhat.com>
    Cc: Jessica Yu <jeyu@kernel.org>
    Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
    Signed-off-by: Jessica Yu <jeyu@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/module.c | 6 ++----
    1 file changed, 2 insertions(+), 4 deletions(-)

    diff --git a/kernel/module.c b/kernel/module.c
    index 94528b891027..4b372c14d9a1 100644
    --- a/kernel/module.c
    +++ b/kernel/module.c
    @@ -3391,8 +3391,7 @@ static bool finished_loading(const char *name)
    sched_annotate_sleep();
    mutex_lock(&module_mutex);
    mod = find_module_all(name, strlen(name), true);
    - ret = !mod || mod->state == MODULE_STATE_LIVE
    - || mod->state == MODULE_STATE_GOING;
    + ret = !mod || mod->state == MODULE_STATE_LIVE;
    mutex_unlock(&module_mutex);

    return ret;
    @@ -3560,8 +3559,7 @@ static int add_unformed_module(struct module *mod)
    mutex_lock(&module_mutex);
    old = find_module_all(mod->name, strlen(mod->name), true);
    if (old != NULL) {
    - if (old->state == MODULE_STATE_COMING
    - || old->state == MODULE_STATE_UNFORMED) {
    + if (old->state != MODULE_STATE_LIVE) {
    /* Wait in case it fails to load. */
    mutex_unlock(&module_mutex);
    err = wait_event_interruptible(module_wq,
    --
    2.20.1
    \
     
     \ /
      Last update: 2019-07-26 16:09    [W:4.744 / U:0.644 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site