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tracing: Use pr_err() instead of WARN() for memory failures 

As warnings can trigger panics, especially when "panic_on_warn" is set,
memory failure warnings can cause panics and fail fuzz testers that are
stressing memory.

Create a MEM_FAIL() macro to use instead of WARN() in the tracing code
(perhaps this should be a kernel wide macro?), and use that for memory
failure issues. This should stop failing fuzz tests due to warnings.

Link: https://lore.kernel.org/r/CACT4Y+ZP-7np20GVRu3p+eZys9GPtbu+JpfV+HtsufAzvTgJrg@mail.gmail.com

Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2020-01-25 10:52:30 -05:00
parent 28394da258
commit 24589e3a20
3 changed files with 23 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
kernel/trace/ftrace.c
View File

@ -5459,7 +5459,7 @@ static void __init set_ftrace_early_graph(char *buf, int enable)
struct ftrace_hash *hash;
hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
if (WARN_ON(!hash))
if (MEM_FAIL(!hash, "Failed to allocate hash\n"))
return;
while (buf) {
@ -6591,7 +6591,7 @@ static void add_to_clear_hash_list(struct list_head *clear_list,
func = kmalloc(sizeof(*func), GFP_KERNEL);
if (!func) {
WARN_ONCE(1, "alloc failure, ftrace filter could be stale\n");
MEM_FAIL(1, "alloc failure, ftrace filter could be stale\n");
return;
}

18
kernel/trace/trace.c
View File

@ -3126,7 +3126,7 @@ static int alloc_percpu_trace_buffer(void)
struct trace_buffer_struct *buffers;
buffers = alloc_percpu(struct trace_buffer_struct);
if (WARN(!buffers, "Could not allocate percpu trace_printk buffer"))
if (MEM_FAIL(!buffers, "Could not allocate percpu trace_printk buffer"))
return -ENOMEM;
trace_percpu_buffer = buffers;
@ -7932,7 +7932,7 @@ static struct dentry *tracing_dentry_percpu(struct trace_array *tr, int cpu)
tr->percpu_dir = tracefs_create_dir("per_cpu", d_tracer);
WARN_ONCE(!tr->percpu_dir,
MEM_FAIL(!tr->percpu_dir,
"Could not create tracefs directory 'per_cpu/%d'\n", cpu);
return tr->percpu_dir;
@ -8253,7 +8253,7 @@ create_trace_option_files(struct trace_array *tr, struct tracer *tracer)
for (cnt = 0; opts[cnt].name; cnt++) {
create_trace_option_file(tr, &topts[cnt], flags,
&opts[cnt]);
WARN_ONCE(topts[cnt].entry == NULL,
MEM_FAIL(topts[cnt].entry == NULL,
"Failed to create trace option: %s",
opts[cnt].name);
}
@ -8437,7 +8437,7 @@ static int allocate_trace_buffers(struct trace_array *tr, int size)
#ifdef CONFIG_TRACER_MAX_TRACE
ret = allocate_trace_buffer(tr, &tr->max_buffer,
allocate_snapshot ? size : 1);
if (WARN_ON(ret)) {
if (MEM_FAIL(ret, "Failed to allocate trace buffer\n")) {
ring_buffer_free(tr->array_buffer.buffer);
tr->array_buffer.buffer = NULL;
free_percpu(tr->array_buffer.data);
@ -8726,7 +8726,7 @@ static __init void create_trace_instances(struct dentry *d_tracer)
trace_instance_dir = tracefs_create_instance_dir("instances", d_tracer,
instance_mkdir,
instance_rmdir);
if (WARN_ON(!trace_instance_dir))
if (MEM_FAIL(!trace_instance_dir, "Failed to create instances directory\n"))
return;
}
@ -8796,7 +8796,7 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
#endif
if (ftrace_create_function_files(tr, d_tracer))
WARN(1, "Could not allocate function filter files");
MEM_FAIL(1, "Could not allocate function filter files");
#ifdef CONFIG_TRACER_SNAPSHOT
trace_create_file("snapshot", 0644, d_tracer,
@ -9348,8 +9348,7 @@ __init static int tracer_alloc_buffers(void)
/* TODO: make the number of buffers hot pluggable with CPUS */
if (allocate_trace_buffers(&global_trace, ring_buf_size) < 0) {
printk(KERN_ERR "tracer: failed to allocate ring buffer!\n");
WARN_ON(1);
MEM_FAIL(1, "tracer: failed to allocate ring buffer!\n");
goto out_free_savedcmd;
}
@ -9422,7 +9421,8 @@ void __init early_trace_init(void)
if (tracepoint_printk) {
tracepoint_print_iter =
kmalloc(sizeof(*tracepoint_print_iter), GFP_KERNEL);
if (WARN_ON(!tracepoint_print_iter))
if (MEM_FAIL(!tracepoint_print_iter,
"Failed to allocate trace iterator\n"))
tracepoint_printk = 0;
else
static_key_enable(&tracepoint_printk_key.key);

12
kernel/trace/trace.h
View File

@ -94,6 +94,18 @@ enum trace_type {
#include "trace_entries.h"
/* Use this for memory failure errors */
#define MEM_FAIL(condition, fmt, ...) ({ \
static bool __section(.data.once) __warned; \
int __ret_warn_once = !!(condition); \
\
if (unlikely(__ret_warn_once && !__warned)) { \
__warned = true; \
pr_err("ERROR: " fmt, ##__VA_ARGS__); \
} \
unlikely(__ret_warn_once); \
})
/*
* syscalls are special, and need special handling, this is why
* they are not included in trace_entries.h