From mboxrd@z Thu Jan 1 00:00:00 1970 From: martin@leisener.de (Martin Leisener) Date: Mon, 08 Jun 2015 11:19:09 +0200 Subject: [lttng-dev] [PATCH lttng-modules] Fix: Building the event list fails on fragmented memory Message-ID: <55755E0D.7010902@leisener.de> Hi Mathieu, thanks for merging my arm patch! I found one more issue during my lttng-modules usages, which can happen in low/fragmented memory situations. Please have a look, if you find this patch useful/mergable. Again it is tested on x86 Ubuntu 12.04 LTS as well as my imx6 arm board. Regards Martin On a small arm imx6 solo with 256MB RAM it often happens that memory becomes fragmented rather quickly, so that kmalloc will not be able to get enough consecutive pages (enocuntered for example if you enable all kernel events: lttng enable-event -k syscall --all). This patch switches the allocation to vmalloc. Tested for x86 on Ubuntu 12.04 Lts and on imx6 solo 256MB RAM If this patch is not applied, you can identify low and/or fragmented memory failures by looking at the kernel ring buffer (please ignore DMA, it is due to some memory setup misconfiguration, should read Normal): ... [ 321.993820] lttng-sessiond: page allocation failure: order:4, mode:0x1040d0 ... [ 321.994711] lowmem_reserve[]: 0 0 0 [ 321.994727] DMA: 801*4kB (UEMC) 424*8kB (EMC) 355*16kB (UEMC) 344*32kB (MC) 340*64kB (C) 8*128kB (C) 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB 0*8192kB 0*16384kB 0*32768kB = 46068kB Signed-off-by: Martin Leisener --- lttng-events.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/lttng-events.c b/lttng-events.c index 7eec04c..c861f71 100644 --- a/lttng-events.c +++ b/lttng-events.c @@ -39,6 +39,7 @@ #include "wrapper/file.h" #include #include +#include #include "wrapper/uuid.h" #include "wrapper/vmalloc.h" /* for wrapper_vmalloc_sync_all() */ @@ -132,10 +133,10 @@ struct lttng_session *lttng_session_create(void) GFP_KERNEL); if (!metadata_cache) goto err_free_session; - metadata_cache->data = kzalloc(METADATA_CACHE_DEFAULT_SIZE, - GFP_KERNEL); + metadata_cache->data = vmalloc(METADATA_CACHE_DEFAULT_SIZE); if (!metadata_cache->data) goto err_free_cache; + memset(metadata_cache->data, 0, METADATA_CACHE_DEFAULT_SIZE); metadata_cache->cache_alloc = METADATA_CACHE_DEFAULT_SIZE; kref_init(&metadata_cache->refcount); session->metadata_cache = metadata_cache; @@ -162,7 +163,7 @@ void metadata_cache_destroy(struct kref *kref) { struct lttng_metadata_cache *cache = container_of(kref, struct lttng_metadata_cache, refcount); - kfree(cache->data); + vfree(cache->data); kfree(cache); } @@ -1523,10 +1524,15 @@ int lttng_metadata_printf(struct lttng_session *session, tmp_cache_alloc_size = max_t(unsigned int, session->metadata_cache->cache_alloc + len, session->metadata_cache->cache_alloc << 1); - tmp_cache_realloc = krealloc(session->metadata_cache->data, - tmp_cache_alloc_size, GFP_KERNEL); + tmp_cache_realloc = vmalloc(tmp_cache_alloc_size); if (!tmp_cache_realloc) goto err; + else if (session->metadata_cache->data) { + memset(tmp_cache_realloc, 0, tmp_cache_alloc_size); + memcpy(tmp_cache_realloc, session->metadata_cache->data, session->metadata_cache->cache_alloc); + vfree(session->metadata_cache->data); + } + session->metadata_cache->cache_alloc = tmp_cache_alloc_size; session->metadata_cache->data = tmp_cache_realloc; } -- 1.7.9.5