X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=lib%2Fringbuffer%2Fring_buffer_backend.c;h=8207f764377a34f5cb0fda0e41da8e56985dbd45;hb=1f0ab1eb0409d23de5f67cc588c3ea4cee4d10e0;hp=54c62a996764ee2ee004ee96f3a188801ae6d871;hpb=9f36eaed6f91d5897924b551b44d1edd8cee00e2;p=lttng-modules.git

diff --git a/lib/ringbuffer/ring_buffer_backend.c b/lib/ringbuffer/ring_buffer_backend.c
index 54c62a99..8207f764 100644
--- a/lib/ringbuffer/ring_buffer_backend.c
+++ b/lib/ringbuffer/ring_buffer_backend.c
@@ -12,6 +12,7 @@
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
+#include <linux/oom.h>
 #include <linux/cpu.h>
 #include <linux/mm.h>
 #include <linux/vmalloc.h>
@@ -43,6 +44,23 @@ int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config *config
 	unsigned long i;
 
 	num_pages = size >> PAGE_SHIFT;
+
+	/*
+	 * Verify that the number of pages requested for that buffer is smaller
+	 * than the number of available pages on the system. si_mem_available()
+	 * returns an _estimate_ of the number of available pages.
+	 */
+	if (num_pages > si_mem_available())
+		goto not_enough_pages;
+
+	/*
+	 * Set the current user thread as the first target of the OOM killer.
+	 * If the estimate received by si_mem_available() was off, and we do
+	 * end up running out of memory because of this buffer allocation, we
+	 * want to kill the offending app first.
+	 */
+	set_current_oom_origin();
+
 	num_pages_per_subbuf = num_pages >> get_count_order(num_subbuf);
 	subbuf_size = chanb->subbuf_size;
 	num_subbuf_alloc = num_subbuf;
@@ -137,6 +155,7 @@ int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config *config
 	 * will not fault.
 	 */
 	wrapper_vmalloc_sync_all();
+	clear_current_oom_origin();
 	vfree(pages);
 	return 0;
 
@@ -153,6 +172,8 @@ depopulate:
 array_error:
 	vfree(pages);
 pages_error:
+	clear_current_oom_origin();
+not_enough_pages:
 	return -ENOMEM;
 }
 
@@ -455,9 +476,11 @@ int channel_backend_init(struct channel_backend *chanb,
 free_bufs:
 	if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
-		ret = cpuhp_state_remove_instance(lttng_rb_hp_prepare,
-				&chanb->cpuhp_prepare.node);
-		WARN_ON(ret);
+		/*
+		 * Teardown of lttng_rb_hp_prepare instance
+		 * on "add" error is handled within cpu hotplug,
+		 * no teardown to do from the caller.
+		 */
 #else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
 #ifdef CONFIG_HOTPLUG_CPU
 		put_online_cpus();