From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-f194.google.com (mail-lj1-f194.google.com [209.85.208.194]) (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 AC8854696C3 for ; Fri, 14 Feb 2020 16:22:47 +0300 (MSK) Received: by mail-lj1-f194.google.com with SMTP id r19so10719597ljg.3 for ; Fri, 14 Feb 2020 05:22:47 -0800 (PST) From: Cyrill Gorcunov Date: Fri, 14 Feb 2020 16:22:20 +0300 Message-Id: <20200214132220.29830-3-gorcunov@gmail.com> In-Reply-To: <20200214132220.29830-1-gorcunov@gmail.com> References: <20200214132220.29830-1-gorcunov@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [Tarantool-patches] [PATCH v8 2/2] fiber: leak slab if unable to bring prots back List-Id: Tarantool development patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: tml Cc: Vladislav Shpilevoy In case if we unable to revert guard page back to read|write we should never use such slab again. Initially I thought of just put panic here and exit but it is too destructive. I think better print an error and continue. If node admin ignore this message then one moment at future there won't be slab left for use and creating new fibers get prohibited. In future (hopefully near one) we plan to drop guard pages to prevent VMA fracturing and use stack marks instead. Reviewed-by: Alexander Turenko Signed-off-by: Cyrill Gorcunov --- src/lib/core/fiber.c | 11 +++++++++-- test/unit/fiber_stack.c | 36 +++++++++++++++++++++++++++++++++--- test/unit/fiber_stack.result | 5 ++++- 3 files changed, 46 insertions(+), 6 deletions(-) diff --git a/src/lib/core/fiber.c b/src/lib/core/fiber.c index f10687b29..73de7765b 100644 --- a/src/lib/core/fiber.c +++ b/src/lib/core/fiber.c @@ -1055,15 +1055,22 @@ fiber_stack_destroy(struct fiber *fiber, struct slab_cache *slabc) * to setup the original protection back in * background. * + * For now lets keep such slab referenced and + * leaked: if mprotect failed we must not allow + * to reuse such slab with PROT_NONE'ed page + * inside. + * * Note that in case if we're called from * fiber_stack_create() the @a mprotect_flags is * the same as the slab been created with, so * calling mprotect for VMA with same flags * won't fail. */ - diag_log(); + say_syserror("fiber: Can't put guard page to slab. " + "Leak %zu bytes", (size_t)fiber->stack_size); + } else { + slab_put(slabc, fiber->stack_slab); } - slab_put(slabc, fiber->stack_slab); } } diff --git a/test/unit/fiber_stack.c b/test/unit/fiber_stack.c index 103dfaf0d..41abe3764 100644 --- a/test/unit/fiber_stack.c +++ b/test/unit/fiber_stack.c @@ -15,11 +15,13 @@ noop_f(va_list ap) static int main_f(va_list ap) { + struct slab_cache *slabc = &cord()->slabc; + size_t used_before, used_after; struct errinj *inj; struct fiber *fiber; header(); - plan(4); + plan(6); /* * Set non-default stack size to prevent reusing of an @@ -47,8 +49,7 @@ main_f(va_list ap) ok(diag_get() != NULL, "mprotect: diag is armed after error"); /* - * Check madvise. We can't test the fiber destroy - * path since it is cleaning error. + * Check madvise error on fiber creation. */ diag_clear(diag_get()); inj = errinj(ERRINJ_FIBER_MADVISE, ERRINJ_BOOL); @@ -59,6 +60,35 @@ main_f(va_list ap) ok(fiber != NULL, "madvise: non critical error on madvise hint"); ok(diag_get() != NULL, "madvise: diag is armed after error"); + /* + * Check if we leak on fiber destruction. + * We will print an error and result get + * compared by testing engine. + */ + fiber_attr_delete(fiber_attr); + fiber_attr = fiber_attr_new(); + fiber_attr->flags |= FIBER_CUSTOM_STACK; + fiber_attr->stack_size = 64 << 10; + + diag_clear(diag_get()); + + used_before = slabc->allocated.stats.used; + + fiber = fiber_new_ex("test_madvise", fiber_attr, noop_f); + ok(fiber != NULL, "fiber with custom stack"); + fiber_set_joinable(fiber, true); + + inj = errinj(ERRINJ_FIBER_MPROTECT, ERRINJ_INT); + inj->iparam = PROT_READ | PROT_WRITE; + + fiber_start(fiber); + fiber_join(fiber); + inj->iparam = -1; + + used_after = slabc->allocated.stats.used; + ok(used_after > used_before, "expected leak detected"); + + fiber_attr_delete(fiber_attr); footer(); ev_break(loop(), EVBREAK_ALL); diff --git a/test/unit/fiber_stack.result b/test/unit/fiber_stack.result index 43ff74b2f..7cae4e96c 100644 --- a/test/unit/fiber_stack.result +++ b/test/unit/fiber_stack.result @@ -1,8 +1,11 @@ SystemError fiber mprotect failed: Cannot allocate memory +fiber: Can't put guard page to slab. Leak 57344 bytes: Cannot allocate memory *** main_f *** -1..4 +1..6 ok 1 - mprotect: failed to setup fiber guard page ok 2 - mprotect: diag is armed after error ok 3 - madvise: non critical error on madvise hint ok 4 - madvise: diag is armed after error +ok 5 - fiber with custom stack +ok 6 - expected leak detected *** main_f: done *** -- 2.20.1