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 38BB0C47258 for ; Sun, 28 Jan 2024 19:43:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7BEC86B0074; Sun, 28 Jan 2024 14:43:33 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 76EA46B0075; Sun, 28 Jan 2024 14:43:33 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 65DD06B0078; Sun, 28 Jan 2024 14:43:33 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 57B076B0074 for ; Sun, 28 Jan 2024 14:43:33 -0500 (EST) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 99CF9806C3 for ; Sun, 28 Jan 2024 19:43:23 +0000 (UTC) X-FDA: 81729743886.19.AC91E05 Received: from out-173.mta1.migadu.com (out-173.mta1.migadu.com [95.215.58.173]) by imf16.hostedemail.com (Postfix) with ESMTP id AF694180004 for ; Sun, 28 Jan 2024 19:43:21 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=n7Nu3PMH; spf=pass (imf16.hostedemail.com: domain of kent.overstreet@linux.dev designates 95.215.58.173 as permitted sender) smtp.mailfrom=kent.overstreet@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1706471002; 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:in-reply-to:references:references:dkim-signature; bh=R6C6f7ya20YN9+Ys4QYnm0jkSEiHBtlfIY2XI0kiOo0=; b=qMGEz/FO1kGPmGuR3SgIJ6HLgTxHBCOWButV+bQEu6kmQ67hB8MGkEA6cOc8Vuml69kThn Iux93vixRTtNGfSV+oeB+CxQybQ11+YKFhnk4RPzZHj9811iRqknSH2MtG2dKBtaeRzi1/ V8vXXMv9+mbXSqOfBtMHfww8vi520Zs= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=n7Nu3PMH; spf=pass (imf16.hostedemail.com: domain of kent.overstreet@linux.dev designates 95.215.58.173 as permitted sender) smtp.mailfrom=kent.overstreet@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1706471002; a=rsa-sha256; cv=none; b=WL3RZmejwvBzwiFiLorQ++arpd2vRE/4FVSfIczldtB47nOJtwhfZXjdwfjsKWOMQZIg1S dOwkr/eOcV0ace0DVhsxHqkAHCJXE/DY1My6ZTN6m4p4by1EQnZwbH+FnfXs09mDAHsHwP 4e4afg8Tbrs9Sbhl9vOjK6Us6QfS9uY= Date: Sun, 28 Jan 2024 14:43:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1706470999; 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: in-reply-to:in-reply-to:references:references; bh=R6C6f7ya20YN9+Ys4QYnm0jkSEiHBtlfIY2XI0kiOo0=; b=n7Nu3PMHmMyz1FEoW4XnATzcA8wCurpwniY8YL5ur/tRz0+o8ZsP8ojxqNI1YUY87Kz5fd VMgG4XBisMaOpt4eiNoLPqIB9lx74RPCrlrOD+9KUkJL/G5q5c91Mt6uyvTXtDtcVece9t NlKODd64KzC1ts4HIbSSLw9QaMu48yM= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Kent Overstreet To: Michal Hocko Cc: linux-mm@kvack.org, Vlastimil Babka , Matthew Wilcox , "Darrick J . Wong" Subject: Re: [PATCH 2/2] mm: introduce PF_MEMALLOC_NOWARN Message-ID: References: <20240126220756.395187-1-kent.overstreet@linux.dev> <20240126220756.395187-2-kent.overstreet@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: AF694180004 X-Rspam-User: X-Stat-Signature: hqhbkdpy456pdfeh5idkh8qkpgu9nsuu X-Rspamd-Server: rspam01 X-HE-Tag: 1706471001-208985 X-HE-Meta: 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 Gjl4hbTD 9OPhdFNTavJ+IKnr93vHggFgidSsQuW9vQKPCx6Ih7S/ZJCsZyyKQC0VMaSwW7N6Cs46y8P4OXMAFWKgQqQ9N+B9kgu4HQUUaWAQVSgBoZBTxn5UWwlnWeHsiYGQxjgOnknAe 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: List-Subscribe: List-Unsubscribe: On Sun, Jan 28, 2024 at 04:45:32PM +0100, Michal Hocko wrote: > On Fri 26-01-24 17:07:56, Kent Overstreet wrote: > > If we're using PF_MEMALLOC, we might have a fallback and might not to > > warn about a failing allocation - thus we need a PF_* equivalent of > > __GFP_NOWARN. > > Could you be more specific about the user? Is this an allocation from > the reclaim path or an explicit PF_MEMALLOC one? It would be also really > helpful to explain why GFP_NOWARN cannot be used directly. Explicit PF_MEMALLOC. It's for a call to alloc_inode(), which doesn't take gfp flags, and plumbing it would require modifying a s_ops callback and would touch every filesystem - but we want to get away from gfp flags anyways :) More specifically, the code where I'm using it is doing a "try GFP_NOWAIT first; if that fails drop locks and do GFP_KERNEL" dance; it's part of a cleanup for some weird lifetime stuff related to fs/inode.c. #define memalloc_flags_do(_flags, _do) \ ({ \ unsigned _saved_flags = memalloc_flags_save(_flags); \ typeof(_do) _ret = _do; \ memalloc_noreclaim_restore(_saved_flags); \ _ret; \ }) /* * Allocate a new inode, dropping/retaking btree locks if necessary: */ static struct bch_inode_info *bch2_new_inode(struct btree_trans *trans) { struct bch_fs *c = trans->c; struct bch_inode_info *inode = memalloc_flags_do(PF_MEMALLOC|PF_MEMALLOC_NOWARN, to_bch_ei(new_inode(c->vfs_sb))); if (unlikely(!inode)) { int ret = drop_locks_do(trans, (inode = to_bch_ei(new_inode(c->vfs_sb))) ? 0 : -ENOMEM); if (ret && inode) discard_new_inode(&inode->v); if (ret) return ERR_PTR(ret); } return inode; }