From 30913c473110ba9969813c05d4db017868772c4d Mon Sep 17 00:00:00 2001 From: Martin Leisener Date: Wed, 10 Jun 2015 15:17:37 +0200 Subject: [PATCH] Fix: Building the event list fails on fragmented memory 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 [ Edit by Mathieu: use vzalloc() rather than vmalloc() + memset 0. ] Signed-off-by: Martin Leisener Signed-off-by: Mathieu Desnoyers --- lttng-events.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/lttng-events.c b/lttng-events.c index 9b3d7669..d8cf337d 100644 --- a/lttng-events.c +++ b/lttng-events.c @@ -34,6 +34,8 @@ #include #include #include +#include + #include "wrapper/uuid.h" #include "wrapper/vmalloc.h" /* for wrapper_vmalloc_sync_all() */ #include "wrapper/random.h" @@ -96,8 +98,7 @@ 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 = vzalloc(METADATA_CACHE_DEFAULT_SIZE); if (!metadata_cache->data) goto err_free_cache; metadata_cache->cache_alloc = METADATA_CACHE_DEFAULT_SIZE; @@ -124,7 +125,7 @@ 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); } @@ -687,10 +688,16 @@ 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 = vzalloc(tmp_cache_alloc_size); if (!tmp_cache_realloc) goto err; + if (session->metadata_cache->data) { + 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; } -- 2.34.1