The patch titled
um: os_dump_core() cleanup
has been added to the -mm tree. Its filename is
um-os_dump_core-cleanup.patch
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------------------------------------------------------
Subject: um: os_dump_core() cleanup
From: Richard Weinberger <richard@xxxxxx>
When os_dump_core() raises SIGTERM to bring down all UML processes this
would also trigger the quite complex do_uml_exitcalls() routine. This is
why UML crashed often while panicking.
Let's make os_dump_core() short and painless by killing all UML processes
with SIGHUP and calling the only sane exit call in this context
(remove_umid_dir()) by hand.
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/um/include/shared/os.h | 1 +
arch/um/os-Linux/umid.c | 2 +-
arch/um/os-Linux/util.c | 22 +++++++---------------
3 files changed, 9 insertions(+), 16 deletions(-)
diff -puN arch/um/include/shared/os.h~um-os_dump_core-cleanup arch/um/include/shared/os.h
--- a/arch/um/include/shared/os.h~um-os_dump_core-cleanup
+++ a/arch/um/include/shared/os.h
@@ -226,6 +226,7 @@ extern int os_get_thread_area(user_desc_
extern int umid_file_name(char *name, char *buf, int len);
extern int set_umid(char *name);
extern char *get_umid(void);
+extern void remove_umid_dir(void);
/* signal.c */
extern void timer_init(void);
diff -puN arch/um/os-Linux/umid.c~um-os_dump_core-cleanup arch/um/os-Linux/umid.c
--- a/arch/um/os-Linux/umid.c~um-os_dump_core-cleanup
+++ a/arch/um/os-Linux/umid.c
@@ -382,7 +382,7 @@ __uml_setup("uml_dir=", set_uml_dir,
" The location to place the pid and umid files.\n\n"
);
-static void remove_umid_dir(void)
+void remove_umid_dir(void)
{
char dir[strlen(uml_dir) + UMID_LEN + 1], err;
diff -puN arch/um/os-Linux/util.c~um-os_dump_core-cleanup arch/um/os-Linux/util.c
--- a/arch/um/os-Linux/util.c~um-os_dump_core-cleanup
+++ a/arch/um/os-Linux/util.c
@@ -103,30 +103,21 @@ void os_dump_core(void)
signal(SIGSEGV, SIG_DFL);
/*
- * We are about to SIGTERM this entire process group to ensure that
- * nothing is around to run after the kernel exits. The
- * kernel wants to abort, not die through SIGTERM, so we
- * ignore it here.
+ * Send SIGHUP to kill non-kernel processes, kernel processes
+ * ignore SIGHUP.
+ * We are using SIGHUP because it has the same effect as SIGTERM
+ * but it does not trigger other signal handlers.
*/
+ kill(0, SIGHUP);
- signal(SIGTERM, SIG_IGN);
- kill(0, SIGTERM);
/*
* Most of the other processes associated with this UML are
* likely sTopped, so give them a SIGCONT so they see the
- * SIGTERM.
+ * SIGHUP.
*/
kill(0, SIGCONT);
/*
- * Now, having sent signals to everyone but us, make sure they
- * die by ptrace. Processes can survive what's been done to
- * them so far - the mechanism I understand is receiving a
- * SIGSEGV and segfaulting immediately upon return. There is
- * always a SIGSEGV pending, and (I'm guessing) signals are
- * processed in numeric order so the SIGTERM (signal 15 vs
- * SIGSEGV being signal 11) is never handled.
- *
* Run a waitpid loop until we get some kind of error.
* Hopefully, it's ECHILD, but there's not a lot we can do if
* it's something else. Tell os_kill_ptraced_process not to
@@ -137,5 +128,6 @@ void os_dump_core(void)
while ((pid = waitpid(-1, NULL, WNOHANG | __WALL)) > 0)
os_kill_ptraced_process(pid, 0);
+ remove_umid_dir();
uml_abort();
}
_
Patches currently in -mm which might be from richard@xxxxxx are
x86-remove-warning-and-warning_symbol-from-struct-stacktrace_ops.patch
mm-mmu_gather-rework.patch
powerpc-mmu_gather-rework.patch
sparc-mmu_gather-rework.patch
s390-mmu_gather-rework.patch
arm-mmu_gather-rework.patch
sh-mmu_gather-rework.patch
ia64-mmu_gather-rework.patch
um-mmu_gather-rework.patch
mm-now-that-all-old-mmu_gather-code-is-gone-remove-the-storage.patch
mm-powerpc-move-the-rcu-page-table-freeing-into-generic-code.patch
mm-extended-batches-for-generic-mmu_gather.patch
lockdep-mutex-provide-mutex_lock_nest_lock.patch
mm-remove-i_mmap_lock-lockbreak.patch
mm-convert-i_mmap_lock-to-a-mutex.patch
mm-revert-page_lock_anon_vma-lock-annotation.patch
mm-improve-page_lock_anon_vma-comment.patch
mm-use-refcounts-for-page_lock_anon_vma.patch
mm-convert-anon_vma-lock-to-a-mutex.patch
mm-optimize-page_lock_anon_vma-fast-path.patch
sh-remove-warning-and-warning_symbol-from-struct-stacktrace_ops.patch
um-fix-uml_lib_path.patch
um-fix-abort.patch
um-remove-sighup-handler.patch
um-os_dump_core-cleanup.patch
lib-consolidate-debug_stack_usage-option.patch
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