When crashkernel=X fails to reserve region under 4G, it will fall back to reserve region above 4G and a region of the default size will also be reserved under 4G. Unfortunately, /sys/kernel/kexec_crash_size only supports one crash kernel region now, the user cannot sense the low memory reserved by reading /sys/kernel/kexec_crash_size. Also, low memory cannot be freed by writing this file. For example: resource_size(crashk_res) = 512M resource_size(crashk_low_res) = 256M The result of 'cat /sys/kernel/kexec_crash_size' is 512M, but it should be 768M. When we execute 'echo 0 > /sys/kernel/kexec_crash_size', the size of crashk_res becomes 0 and resource_size(crashk_low_res) is still 256 MB, which is incorrect. Since crashk_res manages the memory with high address and crashk_low_res manages the memory with low address, crashk_low_res is shrunken only when all crashk_res is shrunken. And because when there is only one crash kernel region, crashk_res is always used. Therefore, if all crashk_res is shrunken and crashk_low_res still exists, swap them. Zhen Lei (6): kexec: fix a memory leak in crash_shrink_memory() kexec: delete a useless check in crash_shrink_memory() kexec: clear crashk_res if all its memory has been released kexec: improve the readability of crash_shrink_memory() kexec: add helper __crash_shrink_memory() kexec: enable kexec_crash_size to support two crash kernel regions kernel/kexec_core.c | 92 +++++++++++++++++++++++++++++++-------------- 1 file changed, 64 insertions(+), 28 deletions(-) -- 2.25.1 _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
