From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C99643D34A5 for ; Fri, 20 Mar 2026 18:14:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774030495; cv=none; b=VBuq0MGknnDfV+TN3WHnGjDAH3KEx+Fnet7NVOg7iBRgUH29M21OtyWhtScE/VdlMGtGcYnfHRx2jLNQl8dwgyEAqvm5Ulqthtv6dzcrBa1HtaHMQI496Q8cT78gQGwxPKVGr2mXuMUvOdnkOk6POxuDMNuINtU/LlxozL3bxHc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774030495; c=relaxed/simple; bh=2ud9VVAGIb5J70qS+Aq6s18YBJv2+0N0qOqGnKGdgDk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=HwPGFuQyYOBfykwMOY7zZbsFsi8PI92D9+9lCnBo9L8dpicSshriSa/sCWSq7VXc7HWe4h1YoSXdJV+LVyIIY0kWAkxq2oZhIm67lIi0AD/B4W5yVdTcGcFTPOYNe7HwJ+nMJA+qlYfhSDwHM/ZToKflbW2gYgIWi3USIyXzG5E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ee5VGMoe; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ee5VGMoe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0E187C4CEF7; Fri, 20 Mar 2026 18:14:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774030495; bh=2ud9VVAGIb5J70qS+Aq6s18YBJv2+0N0qOqGnKGdgDk=; h=From:To:Cc:Subject:Date:From; b=Ee5VGMoe+t1f0NUSaMeg/sco6qzmM6ZNRxu4N8IG5OP4PVX5FiPArqac31P1/7EtH HZz2E+aTuhNaRchPmfEjZI7clp9RAxbklKrbXDDIyK/rbb49IUqtKvB+7ldapRt/4R +W/NHE386gOb5/wnEgIOqkgtbWMU3EJTMvVNm/zxrtATibPBZBO+XHxddlu2BOCXlU DqFjzcraHrG7Y8sWJDkQ+LY5Av05wozxumH8l+VCcJ8KJ0DRUeXD+Aue8vFLiTxkhQ 15LtpqCPguOUxuidWaulPkClTGQtHjnOgMqIfyL+cKu741hcJud1OHbtAE/dmWAg2E ZbyklwE5H2MFw== From: "Lorenzo Stoakes (Oracle)" To: Andrew Morton Cc: David Hildenbrand , Zi Yan , Baolin Wang , "Liam R . Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kiryl Shutsemau , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 00/13] mm/huge_memory: refactor zap_huge_pmd() Date: Fri, 20 Mar 2026 18:14:50 +0000 Message-ID: X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The zap_huge_pmd() function is overly complicated, clean it up and also add an assert in the case that we encounter a buggy PMD entry that doesn't match expectations. This is motivated by a bug discovered [0] where the PMD entry was none of: * A non-DAX, PFN or mixed map. * The huge zero folio * A present PMD entry * A softleaf entry In zap_huge_pmd(), but due to the bug we manged to reach this code. It is useful to explicitly call this out rather than have an arbitrary NULL pointer dereference happen, which also improves understanding of what's going on. The series goes further to make use of vm_normal_folio_pmd() rather than implementing custom logic for retrieving the folio, and extends softleaf functionality to provide and use an equivalent softleaf function. [0]:https://lore.kernel.org/all/6b3d7ad7-49e1-407a-903d-3103704160d8@lucifer.local/ v3: * Propagated tags, thanks everybody! * Fixed const vma parameter in vma_is_special_huge() in 1/13 as per Sashiko. * Renamed needs_deposit -> has_deposit as per Kiryl, better describing the situation as we're zapping deposited tables, not depositing them. * Initialised has_deposit to arch_needs_pgtable_deposit(), and updated huge zero page case to account for that as per Kiryl. * Dropped separated logic approach as per Baolin. * Added 'No functional change intended.' caveats. * Removed seemingly superfluous, inconsistent pot-folio_remove_rmap_pmd() mapcount sanity checks. * De-duplicated tlb->mm's. * Separated folio-specific logic into another function. * Added softleaf_is_valid_pmd_entry(), pmd_to_softleaf_folio() functions. * Add and use normal_or_softleaf_folio_pmd() to make use of vm_normal_folio_pmd() and pmd_to_softleaf_folio() for obtaining the folio. * Add and use has_deposited_pgtable() to figure out deposits. * Added a bunch of explanatory comments as per Baolin. v2: * Added tags thanks everybody! * Fixed issue with returning false on bug case potentially looping forever as per Baolin. * Fixed further issue in bug path in 5/8 with double pte unlock. * Add patch to use vm_normal_folio_pmd() as per David. https://lore.kernel.org/all/cover.1773924928.git.ljs@kernel.org/ v1: https://lore.kernel.org/all/cover.1773865827.git.ljs@kernel.org/ Lorenzo Stoakes (Oracle) (13): mm/huge_memory: simplify vma_is_specal_huge() mm/huge: avoid big else branch in zap_huge_pmd() mm/huge_memory: have zap_huge_pmd return a boolean, add kdoc mm/huge_memory: handle buggy PMD entry in zap_huge_pmd() mm/huge_memory: add a common exit path to zap_huge_pmd() mm/huge_memory: remove unnecessary VM_BUG_ON_PAGE() mm/huge_memory: deduplicate zap deposited table call mm/huge_memory: remove unnecessary sanity checks mm/huge_memory: use mm instead of tlb->mm mm/huge_memory: separate out the folio part of zap_huge_pmd() mm: add softleaf_is_valid_pmd_entry(), pmd_to_softleaf_folio() mm/huge_memory: add and use normal_or_softleaf_folio_pmd() mm/huge_memory: add and use has_deposited_pgtable() include/linux/huge_mm.h | 8 +- include/linux/leafops.h | 39 +++++++++- include/linux/mm.h | 16 ---- mm/huge_memory.c | 168 +++++++++++++++++++++++++--------------- 4 files changed, 143 insertions(+), 88 deletions(-) -- 2.53.0