From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f202.google.com (mail-yw1-f202.google.com [209.85.128.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 425544C87 for ; Fri, 7 Oct 2022 20:13:12 +0000 (UTC) Received: by mail-yw1-f202.google.com with SMTP id 00721157ae682-349423f04dbso55302937b3.13 for ; Fri, 07 Oct 2022 13:13:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=eeV/oO6is47iVyXcP5LuzHYXq7ffrhz178EMVmmCZxw=; b=NKdZAGJ/hoQUB4fETy8pvFiPHdAarBjfTlnHaJIjJiyHiOybz5nL4dnIYk7W5NjL+c X9vxJHi9pb+YWzaNXwMtHOoqvCYWk7VT7hCbL2Z671axs0B1BaIlFVc3Rn2YvDXfT+Kb O4anE3O5E52dxTSLEpDDy8DbS+RqQjMjq61zCxtFiNIOyfVkxCpFnyK9c73fATlOkw4E 9Pe5TOM8LHpHuvhkSd8+S3TnolgDA7Dq6iKgRP4TwsljAo3gFUsxXnHlu3vw9cFFnP+S YOxMEYzjw11ecXdq+V/DrjajOyEXf8t7QM2owD9xSEmNVDhF913qTHO908qBXmpsAgEh UZdA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=eeV/oO6is47iVyXcP5LuzHYXq7ffrhz178EMVmmCZxw=; b=srTSN5ySl9rrDADzHn9pgvIBE0YP43c2bNLh3oMfK5fsm9iaE1ag+BD1fzbKlCABkS nKywHl1L4oigpfWkqY8lRiT/oC3ahiaSk5vAjWtUXTsLOYz589XeTZxecHmwYdgYnQUF ZYt6z/lLnAvU/yfB9seMAr7wRb0KrriNzg2+sLS2NrZrbkCfPOUz3DF/lYqnEYZvFXpU DXdocVAneBJOvk0VU2de8O3qX4bF0sppGFkYebux2Jzb8UyU4jm9q/DXDSPA+0iqNHVN OmEAD23YAJ3ta5/S8HFRQ5Z6KrHMXbvZy+JdkFPyWhDmZSjbVthcXtxFejnr+LxFLbf+ x4rg== X-Gm-Message-State: ACrzQf2jizRgA4SfyEAIty4YV9zr+UDEvktD+E/2exwpQSAmi20rNiag CvB3RQpPZ/zNavFXS+OE3ShNdHEjqLkAKLyMg5s= X-Google-Smtp-Source: AMsMyM4YEtZ03hdAxqVrRsO9mX+URt9wi2j6Vm9Rb4R6Fbs4KJlR2KIGkImoRTDrJygPokSaW3y1Ullba7P7Zs/Xe38= X-Received: from ndesaulniers-desktop.svl.corp.google.com ([2620:0:100e:712:35a0:96d6:8c4e:f207]) (user=ndesaulniers job=sendgmr) by 2002:a81:63c6:0:b0:349:37f7:73dd with SMTP id x189-20020a8163c6000000b0034937f773ddmr6290110ywb.368.1665173591307; Fri, 07 Oct 2022 13:13:11 -0700 (PDT) Date: Fri, 7 Oct 2022 13:11:40 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: X-Developer-Key: i=ndesaulniers@google.com; a=ed25519; pk=UIrHvErwpgNbhCkRZAYSX0CFd/XFEwqX3D0xqtqjNug= X-Developer-Signature: v=1; a=ed25519-sha256; t=1665173500; l=2694; i=ndesaulniers@google.com; s=20220923; h=from:subject; bh=2c8iFYi9IODS8rz+uI3eXvt5cNoC+Xak1t9Qy2KomwU=; b=86PIApGJiSWlXPY7m1LwXuZWF8snbRmlzsAvdJLzZYBQVQJCAa1QN4q97mBW9h9GxBeTXlHbMvxK iBEJbg4jBz7K4vSp8B6dSHR26kg/33CjfpMJcJIR5sW51yIDhuuZ X-Mailer: git-send-email 2.38.0.rc2.412.g84df46c1b4-goog Message-ID: <20221007201140.1744961-1-ndesaulniers@google.com> Subject: [PATCH] fs/select: mark do_select noinline_for_stack for 32b From: Nick Desaulniers To: Andrew Morton , Arnd Bergmann Cc: Alexander Viro , Nathan Chancellor , Tom Rix , Xiaoming Ni , Luis Chamberlain , Andi Kleen , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Christoph Hellwig , Eric Dumazet , "Darrick J. Wong" , Greg Kroah-Hartman , Nick Desaulniers Content-Type: text/plain; charset="UTF-8" Effectively a revert of commit ad312f95d41c ("fs/select: avoid clang stack usage warning") Various configs can still push the stack useage of core_sys_select() over the CONFIG_FRAME_WARN threshold (1024B on 32b targets). fs/select.c:619:5: error: stack frame size of 1048 bytes in function 'core_sys_select' [-Werror,-Wframe-larger-than=] core_sys_select() has a large stack allocation for `stack_fds` where it tries to do something equivalent to "small string optimization" to potentially avoid a malloc. core_sys_select() calls do_select() which has another potentially large stack allocation, `table`. Both of these values depend on FRONTEND_STACK_ALLOC. Mix those two large allocation with register spills which are exacerbated by various configs and compiler versions and we can just barely exceed the 1024B limit. Rather than keep trying to find the right value of MAX_STACK_ALLOC or FRONTEND_STACK_ALLOC, mark do_select() as noinline_for_stack for 32b targets. The intent of FRONTEND_STACK_ALLOC is to help potentially avoid a dynamic memory allocation. In that spirit, restore the previous threshold but separate the stack frames for 32b targets. Link: https://lore.kernel.org/lkml/20221006222124.aabaemy7ofop7ccz@google.com/ Fixes: ad312f95d41c ("fs/select: avoid clang stack usage warning") Suggested-by: Arnd Bergmann Signed-off-by: Nick Desaulniers --- fs/select.c | 7 +++++++ include/linux/poll.h | 4 ---- 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/select.c b/fs/select.c index 0ee55af1a55c..945d04b9cf5a 100644 --- a/fs/select.c +++ b/fs/select.c @@ -476,6 +476,13 @@ static inline void wait_key_set(poll_table *wait, unsigned long in, wait->_key |= POLLOUT_SET; } +#ifdef CONFIG_64BIT +#define noinline_for_stack_32b +#else +#define noinline_for_stack_32b noinline_for_stack +#endif + +noinline_for_stack_32b static int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time) { ktime_t expire, *to = NULL; diff --git a/include/linux/poll.h b/include/linux/poll.h index a9e0e1c2d1f2..d1ea4f3714a8 100644 --- a/include/linux/poll.h +++ b/include/linux/poll.h @@ -14,11 +14,7 @@ /* ~832 bytes of stack space used max in sys_select/sys_poll before allocating additional memory. */ -#ifdef __clang__ -#define MAX_STACK_ALLOC 768 -#else #define MAX_STACK_ALLOC 832 -#endif #define FRONTEND_STACK_ALLOC 256 #define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC #define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC base-commit: 93ed07a23fd08b8613f64cf0a15d7fbdaca010fd -- 2.38.0.rc2.412.g84df46c1b4-goog