Prevent allocation of buffers if exceeding available memory

[lttng-modules.git] / lib / ringbuffer / ring_buffer_backend.c

diff --git a/lib/ringbuffer/ring_buffer_backend.c b/lib/ringbuffer/ring_buffer_backend.c
index 7394c86033d24c1f97ff03b80767381e2fabf2b5..d300980dd7fec1204ce8732d0fd0404bdba88c70 100644 (file)
--- a/lib/ringbuffer/ring_buffer_backend.c
+++ b/lib/ringbuffer/ring_buffer_backend.c
@@ -25,6 +25,7 @@
 #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>
@@ -56,6 +57,23 @@ 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;
@@ -150,6 +168,7 @@ 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;
 
@@ -166,6 +185,8 @@ depopulate:
 array_error:
        vfree(pages);
 pages_error:
+       clear_current_oom_origin();
+not_enough_pages:
        return -ENOMEM;
 }