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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E5ADACE9D46 for ; Tue, 6 Jan 2026 15:03:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 583F36B0005; Tue, 6 Jan 2026 10:03:44 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 532286B0095; Tue, 6 Jan 2026 10:03:44 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 413C96B0096; Tue, 6 Jan 2026 10:03:44 -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 2DBF16B0005 for ; Tue, 6 Jan 2026 10:03:44 -0500 (EST) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id F30C81A9877 for ; Tue, 6 Jan 2026 15:03:43 +0000 (UTC) X-FDA: 84301858326.05.F4DA455 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf08.hostedemail.com (Postfix) with ESMTP id EF9FF160003 for ; Tue, 6 Jan 2026 15:03:41 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=iKG6OAaX; spf=pass (imf08.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1767711822; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Q9OtnnmCe1jDCkn7NEbZySGDISsu/5epWmNbA7lpyMo=; b=ycszFNt+ToV77BxjXjMpweP8+FP4NnOpNpjhF9KkXK40SRHEKB9iacim4I/lE+62VWZIxM 2Fz11rRlSGzY0vw65m+KblGxuhQVhlM7CT8JqgMR6DLptRaXyUm5c24K2UOw8OU1wHjfql 8JbZL7ddbj839HNnp4avWevT4pDkFZw= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=iKG6OAaX; spf=pass (imf08.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1767711822; a=rsa-sha256; cv=none; b=PFIjEhaCwM3H1AcP2W/3k1+yROKxBF4F4vhiRfpUOybnx3ijxM4NqE9KKU2twgsTUMC8ul /yb6Y23xrWL3zfVWV8aOazB08hUad9hkEpBjobx66PJvKuIj732EFUPk1LHmHCszQjNUhP pANOQ0NcmgbcSLB3G4tkO1m+Z7oNbik= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id B765F43E72; Tue, 6 Jan 2026 15:03:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99ECAC116C6; Tue, 6 Jan 2026 15:03:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767711820; bh=6PWRTCruCy2T9djEXYIVH4hnSort9aaCvbTjSWdu5AU=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=iKG6OAaXKypLdxRdWrfF8wqoX/pa8DaYhUihXN9PBnElPaKxikr2eCblQ+2JPDFIi 9CHZFzMrsG4j6vRHVjdElsw2gdd6yQR0aaUnoof9xdihy2nc1KX1NXmE16jr0US1wu mEkLNuYE31NRKSQNmg63vyWdM6qQQAEq3HSQXkh8eetANNYT8kTstxqK4x4DJfvGoX yxxPH1JlDu6+Pt0gRdmQZVxMbz+1yOVH0H6CfD9PuXGByFslK+A+Ozwmn1FHEWWeB9 JGIBKFmqmTKuikomCq67l9qYO8c7mplYf499rmaKTMNlybqNW4tyckz4zWHYcb1xqZ 2eEhWS+v/Uovw== Message-ID: <16dd4c62-c763-42fd-9ff1-a6dfcdbab109@kernel.org> Date: Tue, 6 Jan 2026 16:03:35 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/3] mm: only interrupt taking all mm locks on fatal signal To: Mikulas Patocka , =?UTF-8?Q?Michel_D=C3=A4nzer?= Cc: "Liam R. Howlett" , Lorenzo Stoakes , Alex Deucher , =?UTF-8?Q?Christian_K=C3=B6nig?= , Andrew Morton , amd-gfx@lists.freedesktop.org, linux-mm@kvack.org, Vlastimil Babka , Jann Horn , Pedro Falcato References: <7whbqlfrwjr4z2d4bpny3rjyl5tetdyx7ccf52uvby7hgywoym@6l6m2xcytez7> <5dfbf2f9-0948-cd59-5c59-a6ee946ff9f2@redhat.com> From: "David Hildenbrand (Red Hat)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAa2VybmVsLm9yZz7CwY0EEwEIADcWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCaKYhwAIbAwUJJlgIpAILCQQVCgkIAhYCAh4FAheAAAoJEE3eEPcA/4Naa5EP/3a1 9sgS9m7oiR0uenlj+C6kkIKlpWKRfGH/WvtFaHr/y06TKnWn6cMOZzJQ+8S39GOteyCCGADh 6ceBx1KPf6/AvMktnGETDTqZ0N9roR4/aEPSMt8kHu/GKR3gtPwzfosX2NgqXNmA7ErU4puf zica1DAmTvx44LOYjvBV24JQG99bZ5Bm2gTDjGXV15/X159CpS6Tc2e3KvYfnfRvezD+alhF XIym8OvvGMeo97BCHpX88pHVIfBg2g2JogR6f0PAJtHGYz6M/9YMxyUShJfo0Df1SOMAbU1Q Op0Ij4PlFCC64rovjH38ly0xfRZH37DZs6kP0jOj4QdExdaXcTILKJFIB3wWXWsqLbtJVgjR YhOrPokd6mDA3gAque7481KkpKM4JraOEELg8pF6eRb3KcAwPRekvf/nYVIbOVyT9lXD5mJn IZUY0LwZsFN0YhGhQJ8xronZy0A59faGBMuVnVb3oy2S0fO1y/r53IeUDTF1wCYF+fM5zo14 5L8mE1GsDJ7FNLj5eSDu/qdZIKqzfY0/l0SAUAAt5yYYejKuii4kfTyLDF/j4LyYZD1QzxLC MjQl36IEcmDTMznLf0/JvCHlxTYZsF0OjWWj1ATRMk41/Q+PX07XQlRCRcE13a8neEz3F6we 08oWh2DnC4AXKbP+kuD9ZP6+5+x1H1zEzsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCgh Cj/CA/lc/LMthqQ773gauB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseB fDXHA6m4B3mUTWo13nid0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts 6TZ+IrPOwT1hfB4WNC+X2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiu Qmt3yqrmN63V9wzaPhC+xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKB Tccu2AXJXWAE1Xjh6GOC8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvF FFyAS0Nk1q/7EChPcbRbhJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh 2YmnmLRTro6eZ/qYwWkCu8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRk F3TwgucpyPtcpmQtTkWSgDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0L LH63+BrrHasfJzxKXzqgrW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4v q7oFCPsOgwARAQABwsF8BBgBCAAmAhsMFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAmic2qsF CSZYCKEACgkQTd4Q9wD/g1oq0xAAsAnw/OmsERdtdwRfAMpC74/++2wh9RvVQ0x8xXvoGJwZ rk0Jmck1ABIM//5sWDo7eDHk1uEcc95pbP9XGU6ZgeiQeh06+0vRYILwDk8Q/y06TrTb1n4n 7FRwyskKU1UWnNW86lvWUJuGPABXjrkfL41RJttSJHF3M1C0u2BnM5VnDuPFQKzhRRktBMK4 GkWBvXlsHFhn8Ev0xvPE/G99RAg9ufNAxyq2lSzbUIwrY918KHlziBKwNyLoPn9kgHD3hRBa Yakz87WKUZd17ZnPMZiXriCWZxwPx7zs6cSAqcfcVucmdPiIlyG1K/HIk2LX63T6oO2Libzz 7/0i4+oIpvpK2X6zZ2cu0k2uNcEYm2xAb+xGmqwnPnHX/ac8lJEyzH3lh+pt2slI4VcPNnz+ vzYeBAS1S+VJc1pcJr3l7PRSQ4bv5sObZvezRdqEFB4tUIfSbDdEBCCvvEMBgoisDB8ceYxO cFAM8nBWrEmNU2vvIGJzjJ/NVYYIY0TgOc5bS9wh6jKHL2+chrfDW5neLJjY2x3snF8q7U9G EIbBfNHDlOV8SyhEjtX0DyKxQKioTYPOHcW9gdV5fhSz5tEv+ipqt4kIgWqBgzK8ePtDTqRM qZq457g1/SXSoSQi4jN+gsneqvlTJdzaEu1bJP0iv6ViVf15+qHuY5iojCz8fa0= In-Reply-To: <5dfbf2f9-0948-cd59-5c59-a6ee946ff9f2@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: EF9FF160003 X-Stat-Signature: pn6zufmcd3rimftjs5ogoenx6zi4ioz9 X-HE-Tag: 1767711821-119849 X-HE-Meta: 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 AGjZHb9B rb4WYiqgJqhj1vjKywtsoitewPiFd8A/KneH+ZBHbtoVZGiNCyRTahHfi0hWllIuLkFWkreatfK50YNN0kbT5aWoMs7djAR4+hTdKQq2/5sURUb1993nmz3QfiyfA7PVVGIIU8BrlFbEJ0I7ZOQAlZYS2Msn9KhGWAMQoviiD3jsYPlbZ6i62q6XXrMu+9Q/FzbwekjmH6kdh+krq+dLqfRarwRVfEifsvV50xKJCHoFHieZ8oVg+F9Nv4rIUH14iZYg8Kzr8dPnr4LT0lPvk0QR2WV6ok+8sJg4gl+CSFJcbVui7uRjLMif5ZL4bFD1b0yxQQT7gvYtKJQh/FijK9fQwmbWE63DCfvHEf2LbLLbGl1aO9yKTkmAyQif2MV66WZgUWHObSRD5sSg= 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 1/6/26 13:52, Mikulas Patocka wrote: > > > On Tue, 6 Jan 2026, Michel Dänzer wrote: > >> On 1/5/26 19:15, Liam R. Howlett wrote: >>> * Mikulas Patocka [260104 16:17]: >>> >>> I'm not saying it's wrong to change the signal handling, but this is >>> very much working around a bug in userspace constantly hammering a task >>> with signals and then is surprised there is a response that the kernel >>> was interrupted. >> >> I'd go further than that. If user space fails to retry the system call >> in response to -EINTR, that's a user-space bug, period. It can happen >> anytime for any number of other reasons. (That most system calls happen >> to get away without it most of the time doesn't make it not a bug) > > So, I tried this - just for fun - and the machine doesn't even boot. I get > a lot of errors about inability to open particular files on the console. > > Userspace is buggy, according to your definition, regardless of whether > you like it or not. > > Mikulas > > --- > fs/open.c | 3 +++ > 1 file changed, 3 insertions(+) > > Index: linux-2.6/fs/open.c > =================================================================== > --- linux-2.6.orig/fs/open.c 2025-12-31 20:10:31.000000000 +0100 > +++ linux-2.6/fs/open.c 2026-01-06 13:28:01.000000000 +0100 > @@ -1419,6 +1419,9 @@ static int do_sys_openat2(int dfd, const > struct filename *tmp __free(putname) = NULL; > int err; > > + if (current->pid != 1 && !(get_random_u8() & 0x1)) > + return -EINTR; Reading the man [1] page user space is only to expect EINTR in case it is prepared to deal with signals (install signal handlers), no? There are some exception documented: On Linux, even in the absence of signal handlers, certain blocking interfaces can fail with the error EINTR after the process is stopped by one of the stop signals and then resumed via SIGCONT. This behavior is not sanctioned by POSIX.1, and doesn't occur on other systems. The Linux interfaces that display this behavior are: • "Input" socket interfaces, when a timeout (SO_RCVTIMEO) has been set on the socket using setsockopt(2): accept(2), recv(2), recvfrom(2), recvmmsg(2) (also with a non-NULL timeout argument), and recvmsg(2). • "Output" socket interfaces, when a timeout (SO_RCVTIMEO) has been set on the socket using setsockopt(2): connect(2), send(2), sendto(2), and sendmsg(2), if a send timeout (SO_SNDTIMEO) has been set. • epoll_wait(2), epoll_pwait(2). • semop(2), semtimedop(2). • sigtimedwait(2), sigwaitinfo(2). • Linux 3.7 and earlier: read(2) from an inotify(7) file descriptor • Linux 2.6.21 and earlier: futex(2) FUTEX_WAIT, sem_timedwait(3), sem_wait(3). • Linux 2.6.8 and earlier: msgrcv(2), msgsnd(2). • Linux 2.4 and earlier: nanosleep(2). So I would expect that your test code hear breaks user space. [1] https://man7.org/linux/man-pages/man7/signal.7.html -- Cheers David