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 BC3CDC77B73 for ; Mon, 22 May 2023 12:11:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 58FE4900007; Mon, 22 May 2023 08:11:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4C91C900002; Mon, 22 May 2023 08:11:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 34348900007; Mon, 22 May 2023 08:11:53 -0400 (EDT) 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 267A4900002 for ; Mon, 22 May 2023 08:11:53 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id EF767AD77F for ; Mon, 22 May 2023 12:11:52 +0000 (UTC) X-FDA: 80817777264.28.DDAC58F Received: from out-11.mta1.migadu.com (out-11.mta1.migadu.com [95.215.58.11]) by imf20.hostedemail.com (Postfix) with ESMTP id 8724E1C000B for ; Mon, 22 May 2023 12:11:50 +0000 (UTC) Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=JIyvdenJ; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf20.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.11 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1684757510; 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=Imitl3XmvIuYq6/BvAGSFjVEXqrydT3kZuIQR9ROytI=; b=6qwBWfGwISgLV0XPAPMkQUHjj3uCcI/BL0XCLBXzblaNM0uj4UD27L+okNr+2IXeYMw85L GrrO5Mp3N0HY0t8i0qK8oZa1dfCGUFuk6kuEx9hNl+NDhTtkFfpCntfq497A8BIfB6L4Hl O65WSKyzK7TstPPl73x0dwotb5zHSH4= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=JIyvdenJ; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf20.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.11 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1684757510; a=rsa-sha256; cv=none; b=ltDdCezgFAdtgnJXJngk6cz+6nKHKArEpJQGTMLABUomRz167xO036pegfEYFDfkYhnWMh UOLsEOoK05Hlzyg5+hqaMS/NUhIxIw6326Yp7AYrIFEpGyPSELpQpC9WDhGu0cppqdnWkn u0dNSTvqH/0IV+okCAbSYhpmCj2s7E0= Message-ID: <0e3c5937-2f04-25d9-98eb-01e4c2b04150@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1684757508; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Imitl3XmvIuYq6/BvAGSFjVEXqrydT3kZuIQR9ROytI=; b=JIyvdenJTXf8pd0kQ2NvebD93jjazdpK4xa6MgMCaYY2TlYn6la3ZbG7++GB6AIJ2BQUku finxRbja+B1dKyFuDllep0M1mDiaM9YKiIRgutHjRQUQnoW3ZTHbiRXiIPZLPC1Mn1PMBn r1yglYHh+y6svR/SIRs355RT0dUwsPc= Date: Mon, 22 May 2023 20:11:36 +0800 MIME-Version: 1.0 Subject: Re: [PATCH 13/31] mm/hmm: retry if pte_offset_map() fails Content-Language: en-US To: Hugh Dickins , Andrew Morton Cc: Mike Kravetz , Mike Rapoport , "Kirill A. Shutemov" , Matthew Wilcox , David Hildenbrand , Suren Baghdasaryan , Qi Zheng , Yang Shi , Mel Gorman , Peter Xu , Peter Zijlstra , Will Deacon , Yu Zhao , Alistair Popple , Ralph Campbell , Ira Weiny , Steven Price , SeongJae Park , Naoya Horiguchi , Christophe Leroy , Zack Rusin , Jason Gunthorpe , Axel Rasmussen , Anshuman Khandual , Pasha Tatashin , Miaohe Lin , Minchan Kim , Christoph Hellwig , Song Liu , Thomas Hellstrom , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <68a97fbe-5c1e-7ac6-72c-7b9c6290b370@google.com> <2edc4657-b6ff-3d6e-2342-6b60bfccc5b@google.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: <2edc4657-b6ff-3d6e-2342-6b60bfccc5b@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 8724E1C000B X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: 3hwjw37ioya71qnjm33x88ceazmi4x55 X-HE-Tag: 1684757510-196790 X-HE-Meta: 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 HNfSxAmk NlWsXZATc41wVU9yFgOp3d7MJflVYfcMXxoQc4B+NYO6OVlisk5KbxzXCmGzA8qcfv2kqRu9D/BUSiOJOgq5QHFywutu/AOwwvLVrRdnxCjmWI7HRUgzuK2kCH4uPQrZbssbvk0vXNdndC7qoLH7O/fELexF43LE58jrO 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: On 2023/5/22 13:05, Hugh Dickins wrote: > hmm_vma_walk_pmd() is called through mm_walk, but already has a goto > again loop of its own, so take part in that if pte_offset_map() fails. > > Signed-off-by: Hugh Dickins > --- > mm/hmm.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/hmm.c b/mm/hmm.c > index e23043345615..b1a9159d7c92 100644 > --- a/mm/hmm.c > +++ b/mm/hmm.c > @@ -381,6 +381,8 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, > } > > ptep = pte_offset_map(pmdp, addr); > + if (!ptep) > + goto again; > for (; addr < end; addr += PAGE_SIZE, ptep++, hmm_pfns++) { > int r; > I haven't read the entire patch set yet, but taking a note here. The hmm_vma_handle_pte() will unmap pte and then call migration_entry_wait() to remap pte, so this may fail, we need to handle this case like below: diff --git a/mm/hmm.c b/mm/hmm.c index 6a151c09de5e..eb726ff0981c 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -276,7 +276,8 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, if (is_migration_entry(entry)) { pte_unmap(ptep); hmm_vma_walk->last = addr; - migration_entry_wait(walk->mm, pmdp, addr); + if (!migration_entry_wait(walk->mm, pmdp, addr)) + return -EAGAIN; return -EBUSY; } @@ -386,6 +387,8 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, r = hmm_vma_handle_pte(walk, addr, end, pmdp, ptep, hmm_pfns); if (r) { + if (r == -EAGAIN) + goto again; /* hmm_vma_handle_pte() did pte_unmap() */ return r; } Of course, the migration_entry_wait() also needs to be modified. -- Thanks, Qi