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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1wDiqe-00000003w2e-221V; Fri, 17 Apr 2026 13:03:04 +0000 Date: Fri, 17 Apr 2026 14:03:04 +0100 From: Matthew Wilcox To: "David Hildenbrand (Arm)" Cc: ZhengYuan Huang , akpm@linux-foundation.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, baijiaju1990@gmail.com, r33s3n6@gmail.com, zzzccc427@gmail.com Subject: Re: [PATCH] mm: prepare anon_vma before swapin rmap Message-ID: References: <20260417011606.1089985-1-gality369@gmail.com> <66f67e51-819b-4c60-9f61-170db32362a2@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 32CF714000E X-Stat-Signature: yxar9osbf6xix6371mfxs9atj56gjasb X-HE-Tag: 1776430988-238004 X-HE-Meta: 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 MzCa/2Vg 9wfWvmGrA0X17plQjXxQZ8UyJMRsR49siuvbEWBciohDjIC9PbdFAGq7mKQiATtL8HDgCVf195ffcgw+6KBaHPVTf/WbBBGkTKSDBLFAeqGmO4ux205hoJUohPpDtOJwsx/rQlqsBOI8y/8GQzsckhvjIKStIbI36fFt+6AJZJrnmls6rr02Rfwto+cfhflfXWKNJiqDp+vuwJU4s6kvqyj9YXaoRPfp8h+tR9brPeDd2h/wS+wbp3X4DXDymCNUW0YAmo/vXGV8oAOAuuCoJK6oTSGx8Vh9TaglDyYvzxOsYZHc0OxpOZSZo5KzCdnlAGzgB Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Apr 17, 2026 at 01:57:59PM +0200, David Hildenbrand (Arm) wrote: > On 4/17/26 12:53, David Hildenbrand (Arm) wrote: > > On 4/17/26 03:16, ZhengYuan Huang wrote: > >> [BUG] > >> madvise(MADV_HWPOISON) can fault a swap entry back in through > >> get_user_pages_fast() and hit: ... > >> I can reproduce this issue deterministically on v6.18, but I have not > >> been able to reproduce it with the same setup on next-20260415. > > Just speculating, we had > > commit 3b617fd3d317bf9dd7e2c233e56eafef05734c9d > Author: Lorenzo Stoakes > Date: Mon Jan 5 20:11:49 2026 +0000 > > mm/vma: enforce VMA fork limit on unfaulted,faulted mremap merge too > > Go into v6.19. > > Maybe there was a scenario where we could have lost vma->anon_vma during > a merge, resulting in a swapped page in an anon_vma. > > If this cannot be reproduced on 6.19+,there is nothing to worry about. ... except that 6.18 is LTS so we need a fix for that kernel version. And maybe 6.12 as well (a373baed5a9d went into 6.9, so no need to go further back than that)