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 CFFECC02183 for ; Tue, 14 Jan 2025 16:46:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 67C876B0088; Tue, 14 Jan 2025 11:46:44 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 62CD66B0089; Tue, 14 Jan 2025 11:46:44 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4F4C76B008A; Tue, 14 Jan 2025 11:46:44 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 314B56B0088 for ; Tue, 14 Jan 2025 11:46:44 -0500 (EST) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id E0774160B37 for ; Tue, 14 Jan 2025 16:46:43 +0000 (UTC) X-FDA: 83006636286.04.109A934 Received: from mail-ed1-f47.google.com (mail-ed1-f47.google.com [209.85.208.47]) by imf17.hostedemail.com (Postfix) with ESMTP id D0FC140010 for ; Tue, 14 Jan 2025 16:46:41 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=suse.com header.s=google header.b=YuBMcsMw; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf17.hostedemail.com: domain of mhocko@suse.com designates 209.85.208.47 as permitted sender) smtp.mailfrom=mhocko@suse.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1736873202; a=rsa-sha256; cv=none; b=p6CPEEoVC5elidLVOEOFopRWl3qHczM4l6VO6FpExa9iA+P9ewYo6p+03h7+yVTKSgp3xH OmS/vg4aV2on8auj0YxBFXY20r1Q2mw4/TWK2Y2B1SeSGdrnXXfP4FeegueAxb+ImeovUc Np5vKG+eSeIH/8RbDycZvWOQ+GWi1b0= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=suse.com header.s=google header.b=YuBMcsMw; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf17.hostedemail.com: domain of mhocko@suse.com designates 209.85.208.47 as permitted sender) smtp.mailfrom=mhocko@suse.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1736873202; 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=a2BHjXvqFbc3tWWjsYaH/7UzCgd7nB1pFhFnKUVV49g=; b=4og9ie6bhYWyWCAziFhs73/ApKSfT5FT76RzOHr7FqBxKhwThHeITa90iSMl2Or2aC1LXn GObycBADbuzYR2oUwQBGdnmEC7bxo1Rdxqw8rwOC6ZejFO7fTjWRs7ZUURVBOa4XQfFaPK 4U6BUlf4cwWjPW89ZqeptMwO8NZaXYw= Received: by mail-ed1-f47.google.com with SMTP id 4fb4d7f45d1cf-5d3e6274015so9749700a12.0 for ; Tue, 14 Jan 2025 08:46:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1736873200; x=1737478000; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=a2BHjXvqFbc3tWWjsYaH/7UzCgd7nB1pFhFnKUVV49g=; b=YuBMcsMwpUFz7Y2gmOGnMNIDRDL0dqYJYQhGSa4D5h2Jc4uEPwGIO2gchCKIeKYRkj bUmTstDot7D8/U0BYJmfdJlQME5o+IbqYMis3jJSOuFob/2WCBjOFFhpDmrHa7O+zi6D lntKXB2koXZyuoFiXKR8Yft++eXuWvNZ51OPKT6HMW0xFv3laGlheMHlfTSjAMEBl/Xh WRWDtx2KNOukStZ8FWTZpssoObla0thqUpeFxsF6b4uqNyTet/KM7MaQ4s1uGDCmbwIH nb1eMelebHfanODCUr8j6y0P7dLymoTmllz3j2wx21zt9kUfj56T8DT7UbP64ZSrwdSv C1hA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1736873200; x=1737478000; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=a2BHjXvqFbc3tWWjsYaH/7UzCgd7nB1pFhFnKUVV49g=; b=GmYbdzr7pivJgIF7zVpe9WEAcaEgtdvMUJhbTlgRZWM69S6paS1HOjC3S+VXU9UQkk vdGXACdwmJ+9CfdIX6NOc+M5toWlMek70W4P5yShDh/j5rqdVICkioCtzhr4+wpXKuYK q42lhuvcA0M1wY/fS82PIsdj9YPOVDWpMYqNh+r7EvTmX6/eApHlu+5PMKgUjdB4CZzA ZCzMfjNo+Spyvm23PmST0DzRe4lwclgmiItMQy37WQw7n96WZBfxsr4JjYHSVYYng65n bUw8fst0K4pjoJn7VkL6MLWxXC4+j2tP3SIziwI9CH3k2AIAPocRUNdUD7uc9w/pLOat jjlQ== X-Forwarded-Encrypted: i=1; AJvYcCVCoqJNqyKpH8kkKFKLbNYBhZIlSciPdBrMWRZA5SNLcXT8rTZcvO52eo26gn79odmg34Rv3Cs5iA==@kvack.org X-Gm-Message-State: AOJu0YwTucHCa3rtGB8LFNUpo3Kv9al7s3B14MVGVBTEuN1RiqnTgnzh 5QK8M2Q4Ls2SW0rJIbFH/QEnOvgP/1sjJWu9Ax/PHcOjpckefOpg6llPBC3JlDM= X-Gm-Gg: ASbGncu+/uBt7MCJMBH8C+tuYo8MN0zRzgRb4MkfoidqodGe0PmKjBAXuODWSRIPbOr w3l3DXpVg37xXmP9hmLN0zUzaLQpDM/E2z7gARAZXR01J37uNJG/V8L+rKIVAd5v6QzLEWrXR0x mOnvS3cMA+adK4ydDXBggkgkqNCaLTwA8yfBg1knhEN2/77gSE7ELpgjCp3bIynDVYxLJWI1hUW WDJUVpxM9vy+la3u3CtoR7WfGYgJrFxWcKIhJcK01RE5wu67X0renLf1qeWZ4mHdHcMXA== X-Google-Smtp-Source: AGHT+IHPbTGhIrcMN7gSIY4GR5omZuGW4NRVR+gBuMJJgCqPbIEcYAZVtpjD8uuNUx3jv0VoINP82A== X-Received: by 2002:a05:6402:50c9:b0:5d9:a61:e7c9 with SMTP id 4fb4d7f45d1cf-5d972e1bf6fmr24029174a12.20.1736873198702; Tue, 14 Jan 2025 08:46:38 -0800 (PST) Received: from localhost (109-81-90-202.rct.o2.cz. [109.81.90.202]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5d98fe8f68csm6433022a12.0.2025.01.14.08.46.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Jan 2025 08:46:38 -0800 (PST) Date: Tue, 14 Jan 2025 17:46:37 +0100 From: Michal Hocko To: Johannes Weiner Cc: Yosry Ahmed , Rik van Riel , Balbir Singh , Roman Gushchin , hakeel Butt , Muchun Song , Andrew Morton , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, Nhat Pham Subject: Re: [PATCH v2] memcg: allow exiting tasks to write back data to swap Message-ID: References: <20241212115754.38f798b3@fangorn> <20241212183012.GB1026@cmpxchg.org> <20250114160955.GA1115056@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250114160955.GA1115056@cmpxchg.org> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: D0FC140010 X-Stat-Signature: es5ufahrwypjchb9jxc5iski54pfunqi X-Rspam-User: X-HE-Tag: 1736873201-626738 X-HE-Meta: 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 mskyYo22 p0tkWEyRYCI5i2g/g3qTJPZeIIzCARsgLc25AYPmqgdWqwL7ybHSFQzuNsrYJyTVdl29xQ4TgZbFiObpSVIX3EW9gvBeiglvw5UJopomQ2qIvaE1wh0YZlNRTqtcmdASwq9NYru1iA7qCJSPda1utxxdR6cWo5GaQSobdkSxkpVWo3MSVbIMrMotw+sYzcVgEe8Z5c2kRd5De8pbjd67E4VtRwMFAPsN1Zm9+G/9Jumcgv3PEHI05oszMadCkKZ/rbhR8bMPwwunu5bZo+GZyeewzLCkdGG3IKk4upLOxUPRNag+V7wxF33sVEA== 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 Tue 14-01-25 11:09:55, Johannes Weiner wrote: > Hi, > > On Mon, Dec 16, 2024 at 04:39:12PM +0100, Michal Hocko wrote: > > On Thu 12-12-24 13:30:12, Johannes Weiner wrote: [...] > > > If we return -ENOMEM to an OOM victim in a fault, the fault handler > > > will re-trigger OOM, which will find the existing OOM victim and do > > > nothing, then restart the fault. > > > > IIRC the task will handle the pending SIGKILL if the #PF fails. If the > > charge happens from the exit path then we rely on ENOMEM returned from > > gup as a signal to back off. Do we have any caller that keeps retrying > > on ENOMEM? > > We managed to extract a stack trace of the livelocked task: > > obj_cgroup_may_swap > zswap_store > swap_writepage > shrink_folio_list > shrink_lruvec > shrink_node > do_try_to_free_pages > try_to_free_mem_cgroup_pages OK, so this is the reclaim path and it fails due to reasons you mention below. This will retry several times until it hits mem_cgroup_oom which will bail in mem_cgroup_out_of_memory because of task_is_dying (returns true) and retry the charge + reclaim (as the oom killer hasn't done anything) with passed_oom = true this time and eventually got to nomem path and returns ENOMEM. This should propaged -ENOMEM down the path > charge_memcg > mem_cgroup_swapin_charge_folio > __read_swap_cache_async > swapin_readahead > do_swap_page > handle_mm_fault > do_user_addr_fault > exc_page_fault > asm_exc_page_fault > __get_user All the way here and return the failure to futex_cleanup which doesn't retry __get_user on the failure AFAICS (exit_robust_list). But I might be missing something, it's been quite some time since I've looked into futex code. > futex_cleanup > fuxtex_exit_release > do_exit > do_group_exit > get_signal > arch_do_signal_or_restart > exit_to_user_mode_prepare > syscall_exit_to_user_mode > do_syscall > entry_SYSCALL_64 > syscall > > Both memory.max and memory.zswap.max are hit. I don't see how this > could ever make forward progress - the futex fault will retry until it > succeeds. I must be missing something but I do not see the retry, could you point me where this is happening please? -- Michal Hocko SUSE Labs