From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4DC5FC7EE2F for ; Thu, 25 May 2023 12:57:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EE1BE900005; Thu, 25 May 2023 08:57:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E923D280002; Thu, 25 May 2023 08:57:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CE82D900007; Thu, 25 May 2023 08:57:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id B0678900005 for ; Thu, 25 May 2023 08:57:11 -0400 (EDT) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 3F2D7AD82A for ; Thu, 25 May 2023 12:57:11 +0000 (UTC) X-FDA: 80828777862.22.40A4050 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by imf01.hostedemail.com (Postfix) with ESMTP id 2048740016 for ; Thu, 25 May 2023 12:57:08 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=eEuCpdM5; dkim=pass header.d=linutronix.de header.s=2020e header.b="1/sPmaXx"; dmarc=pass (policy=none) header.from=linutronix.de; spf=pass (imf01.hostedemail.com: domain of tglx@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=tglx@linutronix.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1685019429; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding:in-reply-to: references:references:dkim-signature; bh=6uWwBTxz6tojlOj9FGm/76Ept6hCGnDqJKP1bPRYWAo=; b=k3bZsJW7r5ul/j4gF8YTkDz7Uo+NwwCkUMR+G+DV6/as1pOJjWu2+cS6zB1HrHSSjf9Fef ln4LX19/PglVCI+Am+soknmqQaYM2rYiPb5+PLP6a07KglIsz0jyedkBZNXFNT+WLCtLbr nqjWZLqbsco0V9/2lnoFhHmIrpoVdUA= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=eEuCpdM5; dkim=pass header.d=linutronix.de header.s=2020e header.b="1/sPmaXx"; dmarc=pass (policy=none) header.from=linutronix.de; spf=pass (imf01.hostedemail.com: domain of tglx@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=tglx@linutronix.de ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1685019429; a=rsa-sha256; cv=none; b=YrstOnxH9SYjnZGR2bOiUL43HjprHNiSNcIkCUnVWe0z5eh0QvZVs7bOWRZc5zdgPz6lTR m/HnCnyuJiAnRu7ZaOk03Q5L3GDKus3QKA6XMZzZfN2W12fyan9VsMAzwdh2dwmKOo99OS W2U99iBxhuoUk+J+MdCfqyeykp9tD/s= Message-ID: <20230525124504.750481992@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1685019427; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=6uWwBTxz6tojlOj9FGm/76Ept6hCGnDqJKP1bPRYWAo=; b=eEuCpdM5KGDQdp7RZI6/QP67TdvymuqiVzHxXVbhD2+J62fTrqsWtP26XGfyinID/rKEd6 iy4s2cZUqEojbNx8iwlRj7LtqVncQPCMjP9FQcIthP2FZQldDLW5PW/uaM6It4VcrL/r5b BL57sLp+bh0EzDkMnlXhER2EM5XZCQCe4z9F+Wsbw2dInBqHozuaClJXFHB7uQp/oJjnAS QdXeOy4hjBQbogaVIpP2x+gn2qz3dul9PhIdPjM+d6MyEOTin1UPb2ooP4yuMyrDxfvM1A jO7bpFdPOcqTgVFZi64vc8MOZYn0ugEbfLS53AJPhqOA6RcFRbjSH9BR6h1jcQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1685019427; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=6uWwBTxz6tojlOj9FGm/76Ept6hCGnDqJKP1bPRYWAo=; b=1/sPmaXxDPv+7gTvfu++uGcJAGio+8mLgkCwHJK/twdkMZ72ZEZp8A9Oew6Mc2ySuMXgBt jUy19ErdrO4UJuBg== From: Thomas Gleixner To: linux-mm@kvack.org Cc: Andrew Morton , Christoph Hellwig , Uladzislau Rezki , Lorenzo Stoakes , Peter Zijlstra , Baoquan He Subject: [V2 patch 4/6] mm/vmalloc: Check free space in vmap_block lockless References: <20230525122342.109672430@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Date: Thu, 25 May 2023 14:57:07 +0200 (CEST) X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 2048740016 X-Stat-Signature: 5wkrgtqxnxr9k38tuf1nx6r8wa7ge1wg X-Rspam-User: X-HE-Tag: 1685019428-927385 X-HE-Meta: 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 ouyNOaWj uU/MmVTdk4j5nqStD9JcuKKHKe5wTJOuXwJFdUfeBEGRdm6gNYWIjQ+X4igd1TTjhBlLN6ZV4us7W7j6nAlTIXSk5oE/8Daketr7fVFUKCH+AQPgUfaMRLAUNUHuHOBsaa5WYSfzXWzu7Z28HDZA7yPt7/P8G5oj37Jlson4M9zKnOZk= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: vb_alloc() unconditionally locks a vmap_block on the free list to check the free space. This can be done locklessly because vmap_block::free never increases, it's only decreased on allocations. Check the free space lockless and only if that succeeds, recheck under the lock. Signed-off-by: Thomas Gleixner Reviewed-by: Uladzislau Rezki (Sony) --- mm/vmalloc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2168,6 +2168,9 @@ static void *vb_alloc(unsigned long size list_for_each_entry_rcu(vb, &vbq->free, free_list) { unsigned long pages_off; + if (READ_ONCE(vb->free) < (1UL << order)) + continue; + spin_lock(&vb->lock); if (vb->free < (1UL << order)) { spin_unlock(&vb->lock); @@ -2176,7 +2179,7 @@ static void *vb_alloc(unsigned long size pages_off = VMAP_BBMAP_BITS - vb->free; vaddr = vmap_block_vaddr(vb->va->va_start, pages_off); - vb->free -= 1UL << order; + WRITE_ONCE(vb->free, vb->free - (1UL << order)); bitmap_set(vb->used_map, pages_off, (1UL << order)); if (vb->free == 0) { spin_lock(&vbq->lock);