** Description changed:
- With a very basic Wily image, just trigger a crash with sysrq-trigger
- after installing and setting up linux-crashdump and the kexec will fail
- with the following :
+ [SRU justification]
+ This modification is required to fix memory shortage in the kexec booted
kernel that blocks the creation of kernel crash dumps
+
+ [Impact]
+ Without this fix, the kernel crash dump mechanism is unusable without
applying a workaround
+
+ [Fix]
+ Implement use of smaller initrd.img files located in /var/lib/kdump and used
with the definition of KDUMP_KERNEL / KDUMP_INITRD in the config file.
+
+ [Test Case]
+ - Create a system running the standard Wily release
+ - install the linux-crashdump metapackage
+ - Enable the kdump mechanism by setting USE_KDUMP=1 in
/etc/default/kdump-tools
+ - Reboot to activate the crashkernel= kernel variable
+ - execute the following as root to trigger a kernel crash :
+ echo c > /proc/sysrq-trigger
+
+ Without the fix, the kernel crash dump procedure will not complete (see
+ Original description) and will be stopped by the OOM killer.
+
+ With the fix, the kernel crash dump procedure will complete normally.
+
+ [Regression]
+ This is a new implementation, taken from upstream's 1.5.9 version. In the
eventuality that the package is installed without using the new variable
definitions in /etc/default/kdump-tools, the old method will be used and will
lead to the original failure.
+
+
+ [Original description of the problem]
+ With a very basic Wily image, just trigger a crash with sysrq-trigger after
installing and setting up linux-crashdump and the kexec will fail with the
following :
[ 0.334592] Trying to unpack rootfs image as initramfs...
[ 0.649440] swapper/0 invoked oom-killer: gfp_mask=0x200d2, order=0,
oom_score_adj=0
[ 0.650332] swapper/0 cpuset=/ mems_allowed=0
[ 0.650856] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W
4.2.0-7-generic #7-Ubuntu
[ 0.651788] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
Bochs 01/01/2011
[ 0.652691] ffff88002fd906c8 ffff88002fcf76a8 ffffffff817b0465
000000000000000f
[ 0.653556] ffff88002fd90000 ffff88002fcf7738 ffffffff817ae2b5
ffff88002ffc0e28
[ 0.654418] ffff880033c164c0 ffff880033c16530 ffff88002fd90068
ffff88002fcf7748
...
[ 0.682339] Mem-Info:
[756/1897]
[ 0.682599] active_anon:0 inactive_anon:0 isolated_anon:0
[ 0.682599] active_file:2023 inactive_file:0 isolated_file:0
[ 0.682599] unevictable:14845 dirty:0 writeback:0 unstable:0
[ 0.682599] slab_reclaimable:1722 slab_unreclaimable:632
[ 0.682599] mapped:0 shmem:0 pagetables:0 bounce:0
[ 0.682599] free:0 free_pcp:2 free_cma:0
[ 0.685982] Node 0 DMA free:0kB min:0kB low:0kB high:0kB active_anon:0kB
inactive_anon:0kB active_file:0kB inact
ive_file:0kB unevictable:540kB isolated(anon):0kB isolated(file):0kB
present:632kB managed:548kB mlocked:0kB dirty:
- 0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:8kB
slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB
+ 0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:8kB
slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB
unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
writeback_tmp:0kB pages_scanned:540 all_unreclaimab
le? yes
[ 0.690450] lowmem_reserve[]: 0 0 0 0
- [ 0.690928] Node 0 DMA32 free:0kB min:0kB low:0kB high:0kB active_anon:0kB
inactive_anon:0kB active_file:8092kB
+ [ 0.690928] Node 0 DMA32 free:0kB min:0kB low:0kB high:0kB active_anon:0kB
inactive_anon:0kB active_file:8092kB
inactive_file:0kB unevictable:58840kB isolated(anon):0kB isolated(file):0kB
present:130420kB managed:78064kB mlocke
d:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:6880kB
slab_unreclaimable:2528kB kernel_stack:4
64kB pagetables:0kB unstable:0kB bounce:0kB free_pcp:8kB local_pcp:8kB
free_cma:0kB writeback_tmp:0kB pages_scanned
:58840 all_unreclaimable? yes
[ 0.695547] lowmem_reserve[]: 0 0 0 0
[ 0.696049] Node 0 DMA: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB
0*512kB 0*1024kB 0*2048kB 0*4096kB = 0k
B
- [ 0.697335] Node 0 DMA32: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB
0*512kB 0*1024kB 0*2048kB 0*4096kB =
+ [ 0.697335] Node 0 DMA32: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB
0*512kB 0*1024kB 0*2048kB 0*4096kB =
0kB
[ 0.698641] 16868 total pagecache pages
[ 0.699075] 0 pages in swap cache
[ 0.699448] Swap cache stats: add 0, delete 0, find 0/0
[ 0.700029] Free swap = 0kB
[ 0.700356] Total swap = 0kB
[ 0.700679] 32763 pages RAM
[ 0.700991] 0 pages HighMem/MovableOnly
[ 0.701418] 13110 pages reserved
[ 0.701778] 0 pages cma reserved
[ 0.702139] 0 pages hwpoisoned
[ 0.702481] [ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents
oom_score_adj name
[ 0.703423] Kernel panic - not syncing: Out of memory and no killable
processes...
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https://bugs.launchpad.net/bugs/1496317
Title:
kexec fails with OOM killer with the current crashkernel=128 value
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