This patch prints the status of the memory allocation profiling before __show_mem actually prints the detailed allocation info. This way will let us know the `0B` we saw in allocation info is because the profiling is disabled or the allocation is actually 0B. Signed-off-by: Yueyang Pan --- mm/show_mem.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/show_mem.c b/mm/show_mem.c index ecf20a93ea54..fd85a028a926 100644 --- a/mm/show_mem.c +++ b/mm/show_mem.c @@ -427,7 +427,8 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx) nr = alloc_tag_top_users(tags, ARRAY_SIZE(tags), false); if (nr) { - pr_notice("Memory allocations:\n"); + pr_notice("Memory allocations (profiling is currently turned %s):\n", + mem_alloc_profiling_enabled() ? "on" : "off"); for (i = 0; i < nr; i++) { struct codetag *ct = tags[i].ct; struct alloc_tag *tag = ct_to_alloc_tag(ct); -- 2.47.3 In production, show_mem() can be called concurrently from two different entities, for example one from oom_kill_process() another from __alloc_pages_slowpath from another kthread. This patch adds a spinlock and invokes trylock before printing out the kernel alloc info in show_mem(). This way two alloc info won't interleave with each other, which then makes parsing easier. Signed-off-by: Yueyang Pan --- mm/show_mem.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/show_mem.c b/mm/show_mem.c index fd85a028a926..e9701d07549b 100644 --- a/mm/show_mem.c +++ b/mm/show_mem.c @@ -421,7 +421,9 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx) printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages)); #endif #ifdef CONFIG_MEM_ALLOC_PROFILING - { + static DEFINE_SPINLOCK(mem_alloc_profiling_spinlock); + + if (spin_trylock(&mem_alloc_profiling_spinlock)) { struct codetag_bytes tags[10]; size_t i, nr; @@ -448,6 +450,7 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx) ct->lineno, ct->function); } } + spin_unlock(&mem_alloc_profiling_spinlock); } #endif } -- 2.47.3