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Rado Vrbovsky
b8ebc95f9b
JIRA: https://redhat.atlassian.net/browse/RHEL-152191 commit 139560e8b973402140cafeb68c656c1374bd4c20 Author: Song Liu <song@kernel.org> Date: Mon, 13 Oct 2025 10:30:19 -0700 livepatch: Match old_sympos 0 and 1 in klp_find_func() When there is only one function of the same name, old_sympos of 0 and 1 are logically identical. Match them in klp_find_func(). This is to avoid a corner case with different toolchain behavior. In this specific issue, two versions of kpatch-build were used to build livepatch for the same kernel. One assigns old_sympos == 0 for unique local functions, the other assigns old_sympos == 1 for unique local functions. Both versions work fine by themselves. (PS: This behavior change was introduced in a downstream version of kpatch-build. This change does not exist in upstream kpatch-build.) However, during livepatch upgrade (with the replace flag set) from a patch built with one version of kpatch-build to the same fix built with the other version of kpatch-build, livepatching fails with errors like: [ 14.218706] sysfs: cannot create duplicate filename 'xxx/somefunc,1' ... [ 14.219466] Call Trace: [ 14.219468] <TASK> [ 14.219469] dump_stack_lvl+0x47/0x60 [ 14.219474] sysfs_warn_dup.cold+0x17/0x27 [ 14.219476] sysfs_create_dir_ns+0x95/0xb0 [ 14.219479] kobject_add_internal+0x9e/0x260 [ 14.219483] kobject_add+0x68/0x80 [ 14.219485] ? kstrdup+0x3c/0xa0 [ 14.219486] klp_enable_patch+0x320/0x830 [ 14.219488] patch_init+0x443/0x1000 [ccc_0_6] [ 14.219491] ? 0xffffffffa05eb000 [ 14.219492] do_one_initcall+0x2e/0x190 [ 14.219494] do_init_module+0x67/0x270 [ 14.219496] init_module_from_file+0x75/0xa0 [ 14.219499] idempotent_init_module+0x15a/0x240 [ 14.219501] __x64_sys_finit_module+0x61/0xc0 [ 14.219503] do_syscall_64+0x5b/0x160 [ 14.219505] entry_SYSCALL_64_after_hwframe+0x4b/0x53 [ 14.219507] RIP: 0033:0x7f545a4bd96d ... [ 14.219516] kobject: kobject_add_internal failed for somefunc,1 with -EEXIST, don't try to register things with the same name ... This happens because klp_find_func() thinks somefunc with old_sympos==0 is not the same as somefunc with old_sympos==1, and klp_add_object_nops adds another xxx/func,1 to the list of functions to patch. Signed-off-by: Song Liu <song@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> [pmladek@suse.com: Fixed some typos.] Reviewed-by: Petr Mladek <pmladek@suse.com> Tested-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Rado Vrbovsky <rvrbovsk@redhat.com>