79 lines
2.4 KiB
Diff
79 lines
2.4 KiB
Diff
From: Oleg Nesterov <oleg@redhat.com>
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Date: Fri, 23 Mar 2012 15:02:50 -0700
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Subject: [5/5] kmod: make __request_module() killable
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commit 1cc684ab75123efe7ff446eb821d44375ba8fa30 upstream.
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As Tetsuo Handa pointed out, request_module() can stress the system
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while the oom-killed caller sleeps in TASK_UNINTERRUPTIBLE.
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The task T uses "almost all" memory, then it does something which
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triggers request_module(). Say, it can simply call sys_socket(). This
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in turn needs more memory and leads to OOM. oom-killer correctly
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chooses T and kills it, but this can't help because it sleeps in
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TASK_UNINTERRUPTIBLE and after that oom-killer becomes "disabled" by the
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TIF_MEMDIE task T.
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Make __request_module() killable. The only necessary change is that
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call_modprobe() should kmalloc argv and module_name, they can't live in
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the stack if we use UMH_KILLABLE. This memory is freed via
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call_usermodehelper_freeinfo()->cleanup.
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Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
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Signed-off-by: Oleg Nesterov <oleg@redhat.com>
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Cc: Rusty Russell <rusty@rustcorp.com.au>
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Cc: Tejun Heo <tj@kernel.org>
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Cc: David Rientjes <rientjes@google.com>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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---
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kernel/kmod.c | 26 ++++++++++++++++++++++++--
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1 file changed, 24 insertions(+), 2 deletions(-)
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diff --git a/kernel/kmod.c b/kernel/kmod.c
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index 56a29e8..957a7aa 100644
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--- a/kernel/kmod.c
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+++ b/kernel/kmod.c
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@@ -60,6 +60,12 @@ static DECLARE_RWSEM(umhelper_sem);
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*/
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char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
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+static void free_modprobe_argv(struct subprocess_info *info)
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+{
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+ kfree(info->argv[3]); /* check call_modprobe() */
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+ kfree(info->argv);
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+}
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+
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static int call_modprobe(char *module_name, int wait)
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{
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static char *envp[] = {
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@@ -69,10 +75,26 @@ static int call_modprobe(char *module_name, int wait)
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NULL
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};
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- char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
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+ char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL);
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+ if (!argv)
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+ goto out;
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+
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+ module_name = kstrdup(module_name, GFP_KERNEL);
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+ if (!module_name)
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+ goto free_argv;
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+
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+ argv[0] = modprobe_path;
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+ argv[1] = "-q";
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+ argv[2] = "--";
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+ argv[3] = module_name; /* check free_modprobe_argv() */
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+ argv[4] = NULL;
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return call_usermodehelper_fns(modprobe_path, argv, envp,
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- wait, NULL, NULL, NULL);
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+ wait | UMH_KILLABLE, NULL, free_modprobe_argv, NULL);
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+free_argv:
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+ kfree(argv);
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+out:
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+ return -ENOMEM;
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}
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/**
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