Hi Tobias, On Wed, 23 Mar 2022 12:14:59 +0100 Tobias Powalowski <tobias.powalowski@xxxxxxxxxxxxxx> wrote: > Hi, > again me, > I try to load a 900MB ramdisk on a ramfs rootfs with kexec and a 10MB kernel. > With 2800MB RAM assigned to qemu. > Memory free by /proc/memstat: 2.2GB > It keeps on OOM killed while executing: > kexec -l kernel --initrd=initrd.img > I can safely unpack the initrd in the ramfs without getting OOM killed. > What is kexec doing wrong here? I don't think that kexec is doing anything wrong here. The kexec_load syscall is designed in a way that user space prepares everything in a huge buffer and passes a pointer to it to the system call. The systemcall then needs to copy everything from the user buffer to a kernel buffer. So there are three copies of the initrd in memory (including the one in ramfs). Together they take up 3 * 900MB = 2.7GB. So basically all the memory of your guest. You can try using the kexec_file_load systemcall. That at least eliminates the copy in the user buffer so there are only two copies left. 400MB of free memory is still quite scarce, though. Thanks Philipp _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
