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 416C722FDFA for ; Thu, 10 Jul 2025 21:46:17 +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=1752183978; cv=none; b=BeDQQPb4RX4l52fa2GUyMWiB5Au9lISURJhUzUTx3tkQ0o/MyqfeUaiqmvBDQc9rVoGDIghYHFY+TFPky/iAuRwa3yyrbp/7VDY1ZZMBi2it+20Up1arpj5ySolNDWTQu8y5SmaO6ODIMRXg1vgepseomx7ojD/4VEaBay+GfEg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752183978; c=relaxed/simple; bh=6GIxnKoXklB5ST+WUWSXrjrarBO7jkUIGdWC0ijFP84=; h=Date:To:From:Subject:Message-Id; b=mkCFNznZkG056s03fUheN0w7kd5LFCsFFPnN8fSGn1GVOT3UXeXWwLu2/PjyUhESjWCeuTT6Re+2PvmYR47nVMKs2XxDdfL3Iy7lCaxbAJRmCBi6cIbnxnuL4lhMACZkTDHjNER3aSQGXqJkwFkVgAjBkq9d1HGhdjLgjKuvWWQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=JIFqqR6c; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="JIFqqR6c" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A7B87C4CEE3; Thu, 10 Jul 2025 21:46:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1752183977; bh=6GIxnKoXklB5ST+WUWSXrjrarBO7jkUIGdWC0ijFP84=; h=Date:To:From:Subject:From; b=JIFqqR6ci+mY3RjNa8eR5Wt8OkcPbUy9U82wETPggkguZKa7GjQFf1vgNI8Xl6ews jWQEF/fCmnFpBDKuuZwyH4H1viM14oIN9r7LH+SuTZZsrwSdk7vyjBsw/durPkEZg8 Yi5l37INv6xx1S3d3G1Qp3b9sF0B1IFJg5RzEcm0= Date: Thu, 10 Jul 2025 14:46:17 -0700 To: mm-commits@vger.kernel.org,viro@zeniv.linux.org.uk,vbabka@suse.cz,riel@surriel.com,peterx@redhat.com,liam.howlett@oracle.com,jannh@google.com,jack@suse.cz,brauner@kernel.org,lorenzo.stoakes@oracle.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-mremap-refactor-initial-parameter-sanity-checks.patch added to mm-new branch Message-Id: <20250710214617.A7B87C4CEE3@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/mremap: refactor initial parameter sanity checks has been added to the -mm mm-new branch. Its filename is mm-mremap-refactor-initial-parameter-sanity-checks.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mremap-refactor-initial-parameter-sanity-checks.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Lorenzo Stoakes Subject: mm/mremap: refactor initial parameter sanity checks Date: Thu, 10 Jul 2025 16:50:26 +0100 We are currently checking some things later, and some things immediately. Aggregate the checks and avoid ones that need not be made. Simplify things by aligning lengths immediately. Defer setting the delta parameter until later, which removes some duplicate code in the hugetlb case. We can safely perform the checks moved from mremap_to() to check_mremap_params() because: * If we set a new address via vrm_set_new_addr(), then this is guaranteed to not overlap nor to position the new VMA past TASK_SIZE, so there's no need to check these later. * We can simply page align lengths immediately. We do not need to check for overlap nor TASK_SIZE sanity after hugetlb alignment as this asserts addresses are huge-aligned, then huge-aligns lengths, rounding down. This means any existing overlap would have already been caught. Moving things around like this lays the groundwork for subsequent changes to permit operations on batches of VMAs. No functional change intended. Link: https://lkml.kernel.org/r/d6614e35931246cbc68e9d6250552966a407ab45.1752162066.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Vlastimil Babka Cc: Al Viro Cc: Christian Brauner Cc: Jan Kara Cc: Jann Horn Cc: Liam Howlett Cc: Peter Xu Cc: Rik van Riel Signed-off-by: Andrew Morton --- mm/mremap.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) --- a/mm/mremap.c~mm-mremap-refactor-initial-parameter-sanity-checks +++ a/mm/mremap.c @@ -1415,14 +1415,6 @@ static unsigned long mremap_to(struct vm struct mm_struct *mm = current->mm; unsigned long err; - /* Is the new length or address silly? */ - if (vrm->new_len > TASK_SIZE || - vrm->new_addr > TASK_SIZE - vrm->new_len) - return -EINVAL; - - if (vrm_overlaps(vrm)) - return -EINVAL; - if (vrm->flags & MREMAP_FIXED) { /* * In mremap_to(). @@ -1527,7 +1519,12 @@ static unsigned long check_mremap_params * for DOS-emu "duplicate shm area" thing. But * a zero new-len is nonsensical. */ - if (!PAGE_ALIGN(vrm->new_len)) + if (!vrm->new_len) + return -EINVAL; + + /* Is the new length or address silly? */ + if (vrm->new_len > TASK_SIZE || + vrm->new_addr > TASK_SIZE - vrm->new_len) return -EINVAL; /* Remainder of checks are for cases with specific new_addr. */ @@ -1546,6 +1543,10 @@ static unsigned long check_mremap_params if (flags & MREMAP_DONTUNMAP && vrm->old_len != vrm->new_len) return -EINVAL; + /* Target VMA must not overlap source VMA. */ + if (vrm_overlaps(vrm)) + return -EINVAL; + /* * move_vma() need us to stay 4 maps below the threshold, otherwise * it will bail out at the very beginning. @@ -1622,8 +1623,6 @@ static bool align_hugetlb(struct vma_rem if (vrm->new_len > vrm->old_len) return false; - vrm_set_delta(vrm); - return true; } @@ -1723,14 +1722,13 @@ static unsigned long do_mremap(struct vm struct vm_area_struct *vma; unsigned long res; + vrm->old_len = PAGE_ALIGN(vrm->old_len); + vrm->new_len = PAGE_ALIGN(vrm->new_len); + res = check_mremap_params(vrm); if (res) return res; - vrm->old_len = PAGE_ALIGN(vrm->old_len); - vrm->new_len = PAGE_ALIGN(vrm->new_len); - vrm_set_delta(vrm); - if (mmap_write_lock_killable(mm)) return -EINTR; vrm->mmap_locked = true; @@ -1753,6 +1751,7 @@ static unsigned long do_mremap(struct vm goto out; } + vrm_set_delta(vrm); vrm->remap_type = vrm_remap_type(vrm); /* Actually execute mremap. */ _ Patches currently in -mm which might be from lorenzo.stoakes@oracle.com are mm-madvise-remove-the-visitor-pattern-and-thread-anon_vma-state.patch mm-madvise-thread-mm_struct-through-madvise_behavior.patch mm-madvise-thread-vma-range-state-through-madvise_behavior.patch mm-madvise-thread-all-madvise-state-through-madv_behavior.patch mm-madvise-eliminate-very-confusing-manipulation-of-prev-vma.patch mm-madvise-eliminate-very-confusing-manipulation-of-prev-vma-fix.patch tools-testing-selftests-add-mremap-unfaulted-faulted-test-cases.patch mm-mremap-perform-some-simple-cleanups.patch mm-mremap-refactor-initial-parameter-sanity-checks.patch mm-mremap-put-vma-check-and-prep-logic-into-helper-function.patch mm-mremap-cleanup-post-processing-stage-of-mremap.patch mm-mremap-use-an-explicit-uffd-failure-path-for-mremap.patch mm-mremap-check-remap-conditions-earlier.patch mm-mremap-move-remap_is_valid-into-check_prep_vma.patch mm-mremap-clean-up-mlock-populate-behaviour.patch mm-mremap-permit-mremap-move-of-multiple-vmas.patch tools-testing-selftests-extend-mremap_test-to-test-multi-vma-mremap.patch