On 08/13/19 at 10:46am, Dave Young wrote: > Add more cc. > On 08/13/19 at 10:43am, Dave Young wrote: > > Hi, > > > > On 08/12/19 at 11:50am, Michal Hocko wrote: > > > On Mon 12-08-19 11:42:33, Paul Menzel wrote: > > > > Dear Linux folks, > > > > > > > > > > > > On a Dell PowerEdge R7425 with two AMD EPYC 7601 (total 128 threads) and > > > > 1 TB RAM, the crash kernel with 256 MB of space reserved crashes. > > > > > > > > Please find the messages of the normal and the crash kernel attached. > > > > > > You will need more memory to reserve for the crash kernel because ... > > > > > > > [ 4.548703] Node 0 DMA free:484kB min:4kB low:4kB high:4kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:568kB managed:484kB mlocked:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB > > > > [ 4.573612] lowmem_reserve[]: 0 125 125 125 > > > > [ 4.577799] Node 0 DMA32 free:1404kB min:1428kB low:1784kB high:2140kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:15720kB writepending:0kB present:261560kB managed:133752kB mlocked:0kB kernel_stack:2496kB pagetables:0kB bounce:0kB free_pcp:212kB local_pcp:212kB free_cma:0kB > > > > > > ... the memory is really depleted and nothing to be reclaimed (no anon. > > > file pages) Look how tht free memory is below min watermark (node zone DMA has > > > lowmem protection for GFP_KERNEL allocation). > > > > We found similar issue on our side while working on kdump on SME enabled > > systemd. Kairui is working on some patches. > > > > Actually on those SME/SEV enabled machines, swiotlb is enabled > > automatically so at least we need extra 64M+ memory for kdump other > > than the normal expectation. > > > > Can you check if this is also your case? > > The question is to Paul, also it would be always good to cc kexec mail > list for kexec and kdump issues. Looks like hardware iommu is used, maybe you do not enable SME? Also replace maxcpus=1 with nr_cpus=1 can save some memory, can have a try.
