initramfs_test_extract() and friends call unpack_to_rootfs() from a kunit kthread while do_populate_rootfs() may still be running asynchronously from rootfs_initcall. unpack_to_rootfs() keeps its parser state in module-static variables (victim, byte_count, state, this_header, header_buf, name_buf, ...), so the two writers corrupt each other.
On arm64 v7.0-rc5+ this oopses early in boot: Unable to handle kernel paging request at virtual address ffff80018f9f0ffc pc : do_reset+0x3c/0x98 Call trace: do_reset initramfs_test_extract kunit_try_run_case Initramfs unpacking failed: junk within compressed archive do_reset() faults because 'victim' was overwritten by the boot-time unpacker; the boot unpacker meanwhile logs the bogus "junk within compressed archive" on the real initrd because the test wrecked its state machine. Add a suite .init that calls wait_for_initramfs() so the async unpack is quiescent before the first case runs. To: Alexander Viro <[email protected]> To: Christian Brauner <[email protected]> To: Jan Kara <[email protected]> To: David Disseldorp <[email protected]> Cc: [email protected] Fixes: 83c0b27266ec ("initramfs_test: kunit tests for initramfs unpacking") Signed-off-by: Jia He <[email protected]> --- init/initramfs_test.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/init/initramfs_test.c b/init/initramfs_test.c index 2ce38d9a8fd0..eb76f63f302e 100644 --- a/init/initramfs_test.c +++ b/init/initramfs_test.c @@ -3,7 +3,9 @@ #include <linux/fcntl.h> #include <linux/file.h> #include <linux/fs.h> +#include <linux/init.h> #include <linux/init_syscalls.h> +#include <linux/initrd.h> #include <linux/stringify.h> #include <linux/timekeeping.h> #include "initramfs_internal.h" @@ -510,8 +512,21 @@ static struct kunit_case __refdata initramfs_test_cases[] = { {}, }; -static struct kunit_suite initramfs_test_suite = { +static int __init initramfs_test_init(struct kunit *test) +{ + /* + * unpack_to_rootfs() uses module-static state (victim, byte_count, + * state, ...). The boot-time async do_populate_rootfs() may still be + * running, so wait for it to finish before we call unpack_to_rootfs() + * from the test thread, otherwise the two writers race and crash. + */ + wait_for_initramfs(); + return 0; +} + +static struct kunit_suite __refdata initramfs_test_suite = { .name = "initramfs", + .init = initramfs_test_init, .test_cases = initramfs_test_cases, }; kunit_test_init_section_suites(&initramfs_test_suite); -- 2.34.1
