From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-f196.google.com (mail-lj1-f196.google.com [209.85.208.196]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by dev.tarantool.org (Postfix) with ESMTPS id 1B78D46970E for ; Wed, 15 Jan 2020 20:05:41 +0300 (MSK) Received: by mail-lj1-f196.google.com with SMTP id w1so19401516ljh.5 for ; Wed, 15 Jan 2020 09:05:41 -0800 (PST) From: Cyrill Gorcunov Date: Wed, 15 Jan 2020 20:05:23 +0300 Message-Id: <20200115170524.20471-2-gorcunov@gmail.com> In-Reply-To: <20200115170524.20471-1-gorcunov@gmail.com> References: <20200115170524.20471-1-gorcunov@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [Tarantool-patches] [PATCH v2 1/2] fiber: use diag_ logger in fiber_madvise/mprotect failures List-Id: Tarantool development patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: tml Both madvise and mprotect calls can fail due to various reasons, mostly because of lack of free memory in the system. We log such cases via say_x helpers but this is not enough. In particular tarantool/memcached relies on diag error to be set to detect an error condition: | expire_fiber = fiber_new(name, memcached_expire_loop); | const box_error_t *err = box_error_last(); | if (err) { | say_error("Can't start the expire fiber"); | say_error("%s", box_error_message(err)); | return -1; | } Thus lets use diag_set() helper here and instead of macros use inline functions for better readability. Fixes #4722 Reported-by: Alexander Turenko Signed-off-by: Cyrill Gorcunov --- src/lib/core/fiber.c | 70 +++++++++++++++++++++++++++++++++----------- 1 file changed, 53 insertions(+), 17 deletions(-) diff --git a/src/lib/core/fiber.c b/src/lib/core/fiber.c index 00ae8cded..b51f46f2f 100644 --- a/src/lib/core/fiber.c +++ b/src/lib/core/fiber.c @@ -173,21 +173,27 @@ static int (*fiber_invoke)(fiber_func f, va_list ap); #define ASAN_FINISH_SWITCH_FIBER(var_name) #endif -#define fiber_madvise(addr, len, advice) \ -({ \ - int err = madvise((addr), (len), (advice)); \ - if (err) \ - say_syserror("madvise"); \ - err; \ -}) - -#define fiber_mprotect(addr, len, prot) \ -({ \ - int err = mprotect((addr), (len), (prot)); \ - if (err) \ - say_syserror("mprotect"); \ - err; \ -}) +static inline int +fiber_madvise(void *addr, size_t len, int advice) +{ + if (madvise(addr, len, advice) != 0) { + diag_set(SystemError, "fiber madvise %p:%zu:%d failed", + addr, len, advice); + return -1; + } + return 0; +} + +static inline int +fiber_mprotect(void *addr, size_t len, int prot) +{ + if (mprotect(addr, len, prot) != 0) { + diag_set(SystemError, "fiber mprotect %p:%zu:%d failed", + addr, len, prot); + return -1; + } + return 0; +} #if ENABLE_FIBER_TOP static __thread bool fiber_top_enabled = false; @@ -951,6 +957,12 @@ fiber_stack_recycle(struct fiber *fiber) start = page_align_up(fiber->stack_watermark); end = fiber->stack + fiber->stack_size; } + + /* + * Ignore errors on MADV_DONTNEED because this is + * just a hint for OS and not critical for + * functionality. + */ fiber_madvise(start, end - start, MADV_DONTNEED); stack_put_watermark(fiber->stack_watermark); } @@ -969,7 +981,9 @@ fiber_stack_watermark_create(struct fiber *fiber) /* * We don't expect the whole stack usage in regular - * loads, let's try to minimize rss pressure. + * loads, let's try to minimize rss pressure. But do + * not exit if MADV_DONTNEED failed, it is just a hint + * for OS, not critical one. */ fiber_madvise(fiber->stack, fiber->stack_size, MADV_DONTNEED); @@ -1007,6 +1021,8 @@ fiber_stack_watermark_create(struct fiber *fiber) static void fiber_stack_destroy(struct fiber *fiber, struct slab_cache *slabc) { + static const int mprotect_flags = PROT_READ | PROT_WRITE; + if (fiber->stack != NULL) { VALGRIND_STACK_DEREGISTER(fiber->stack_id); #if ENABLE_ASAN @@ -1017,7 +1033,22 @@ fiber_stack_destroy(struct fiber *fiber, struct slab_cache *slabc) guard = page_align_down(fiber->stack - page_size); else guard = page_align_up(fiber->stack + fiber->stack_size); - fiber_mprotect(guard, page_size, PROT_READ | PROT_WRITE); + + if (fiber_mprotect(guard, page_size, mprotect_flags) != 0) { + /* + * FIXME: We need some intelligent handling: + * say put this slab into a queue and retry + * to setup the original protection back in + * background. + * + * Note that in case if we're called from + * fiber_stack_create() the @mprotect_flags is + * the same as the slab been created with, so + * calling mprotect for VMA with same flags + * won't fail. + */ + diag_log(); + } slab_put(slabc, fiber->stack_slab); } } @@ -1064,6 +1095,11 @@ fiber_stack_create(struct fiber *fiber, struct slab_cache *slabc, fiber->stack_size); if (fiber_mprotect(guard, page_size, PROT_NONE)) { + /* + * Write an error into the log since a guard + * page is critical for functionality. + */ + diag_log(); fiber_stack_destroy(fiber, slabc); return -1; } -- 2.20.1