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| author |   Kairui Song <kasong@redhat.com> | 2019-07-16 16:26:39 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-16 19:23:21 -0700 |
| commit | c6c405336bd3b0ebd1d76aaf9ea88b35dba77e61 (patch) | |
| tree | c14276b9e30cc90476ebc9c1da1cf1ab49749c9c /fs/proc | |
| parent | tools/testing/selftests/proc/proc-pid-vm.c: hide "segfault at ffffffffff600000" dmesg spam (diff) | |
| download | wireguard-linux-c6c405336bd3b0ebd1d76aaf9ea88b35dba77e61.tar.xz wireguard-linux-c6c405336bd3b0ebd1d76aaf9ea88b35dba77e61.zip | |
vmcore: add a kernel parameter novmcoredd
Since commit 2724273e8fd0 ("vmcore: add API to collect hardware dump in
second kernel"), drivers are allowed to add device related dump data to
vmcore as they want by using the device dump API. This has a potential
issue, the data is stored in memory, drivers may append too much data
and use too much memory. The vmcore is typically used in a kdump kernel
which runs in a pre-reserved small chunk of memory. So as a result it
will make kdump unusable at all due to OOM issues.
So introduce new 'novmcoredd' command line option. User can disable
device dump to reduce memory usage. This is helpful if device dump is
using too much memory, disabling device dump could make sure a regular
vmcore without device dump data is still available.
[akpm@linux-foundation.org: tweak documentation]
[akpm@linux-foundation.org: vmcore.c needs moduleparam.h]
Link: http://lkml.kernel.org/r/20190528111856.7276-1-kasong@redhat.com
Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Cc: "David S . Miller" <davem@davemloft.net>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/Kconfig | 3 | ||||
| -rw-r--r-- | fs/proc/vmcore.c | 9 |
2 files changed, 11 insertions, 1 deletions
diff --git a/fs/proc/Kconfig b/fs/proc/Kconfig index 4c3dcb718961..cba429db95d9 100644 --- a/fs/proc/Kconfig +++ b/fs/proc/Kconfig @@ -58,7 +58,8 @@ config PROC_VMCORE_DEVICE_DUMP snapshot. If you say Y here, the collected device dumps will be added - as ELF notes to /proc/vmcore. + as ELF notes to /proc/vmcore. You can still disable device + dump using the kernel command line option 'novmcoredd'. config PROC_SYSCTL bool "Sysctl support (/proc/sys)" if EXPERT diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 57957c91c6df..7bcc92add72c 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -21,6 +21,7 @@ #include <linux/init.h> #include <linux/crash_dump.h> #include <linux/list.h> +#include <linux/moduleparam.h> #include <linux/mutex.h> #include <linux/vmalloc.h> #include <linux/pagemap.h> @@ -54,6 +55,9 @@ static struct proc_dir_entry *proc_vmcore; /* Device Dump list and mutex to synchronize access to list */ static LIST_HEAD(vmcoredd_list); static DEFINE_MUTEX(vmcoredd_mutex); + +static bool vmcoredd_disabled; +core_param(novmcoredd, vmcoredd_disabled, bool, 0); #endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */ /* Device Dump Size */ @@ -1452,6 +1456,11 @@ int vmcore_add_device_dump(struct vmcoredd_data *data) size_t data_size; int ret; + if (vmcoredd_disabled) { + pr_err_once("Device dump is disabled\n"); + return -EINVAL; + } + if (!data || !strlen(data->dump_name) || !data->vmcoredd_callback || !data->size) return -EINVAL; |