linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, Linux API <linux-api@vger.kernel.org>,
	David Hildenbrand <david@redhat.com>,
	Arnd Bergmann <arnd@arndb.de>, Michal Hocko <mhocko@suse.com>,
	Oscar Salvador <osalvador@suse.de>,
	Matthew Wilcox <willy@infradead.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Minchan Kim <minchan@kernel.org>, Jann Horn <jannh@google.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Dave Hansen <dave.hansen@intel.com>,
	Hugh Dickins <hughd@google.com>, Rik van Riel <riel@surriel.com>,
	"Michael S . Tsirkin" <mst@redhat.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Richard Henderson <rth@twiddle.net>,
	Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	Matt Turner <mattst88@gmail.com>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Helge Deller <deller@gmx.de>, Chris Zankel <chris@zankel.net>,
	Max Filippov <jcmvbkbc@gmail.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Peter Xu <peterx@redhat.com>,
	Rolf Eike Beer <eike-kernel@sf-tec.de>,
	Ram Pai <linuxram@us.ibm.com>, Shuah Khan <shuah@kernel.org>
Subject: [PATCH v1] mm/madvise: report SIGBUS as -EFAULT for MADV_POPULATE_(READ|WRITE)
Date: Mon, 26 Jul 2021 17:49:32 +0200	[thread overview]
Message-ID: <20210726154932.102880-1-david@redhat.com> (raw)

Doing some extended tests and polishing the man page update for
MADV_POPULATE_(READ|WRITE), I realized that we end up converting also
SIGBUS (via -EFAULT) to -EINVAL, making it look like yet another
madvise() user error.

We want to report only problematic mappings and permission problems that
the user could have know as -EINVAL.

Let's not convert -EFAULT arising due to SIGBUS (or SIGSEGV) to
-EINVAL, but instead indicate -EFAULT to user space. While we could also
convert it to -ENOMEM, using -EFAULT looks more helpful when user space
might want to troubleshoot what's going wrong: MADV_POPULATE_(READ|WRITE)
is not part of an final Linux release and we can still adjust the behavior.

Fixes: 4ca9b3859dac ("mm/madvise: introduce MADV_POPULATE_(READ|WRITE) to prefault page tables")
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rolf Eike Beer <eike-kernel@sf-tec.de>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 mm/gup.c     | 7 +++++--
 mm/madvise.c | 4 +++-
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 42b8b1fa6521..b94717977d17 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1558,9 +1558,12 @@ long faultin_vma_page_range(struct vm_area_struct *vma, unsigned long start,
 		gup_flags |= FOLL_WRITE;
 
 	/*
-	 * See check_vma_flags(): Will return -EFAULT on incompatible mappings
-	 * or with insufficient permissions.
+	 * We want to report -EINVAL instead of -EFAULT for any permission
+	 * problems or incompatible mappings.
 	 */
+	if (check_vma_flags(vma, gup_flags))
+		return -EINVAL;
+
 	return __get_user_pages(mm, start, nr_pages, gup_flags,
 				NULL, NULL, locked);
 }
diff --git a/mm/madvise.c b/mm/madvise.c
index 6d3d348b17f4..5c065bc8b5f6 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -862,10 +862,12 @@ static long madvise_populate(struct vm_area_struct *vma,
 			switch (pages) {
 			case -EINTR:
 				return -EINTR;
-			case -EFAULT: /* Incompatible mappings / permissions. */
+			case -EINVAL: /* Incompatible mappings / permissions. */
 				return -EINVAL;
 			case -EHWPOISON:
 				return -EHWPOISON;
+			case -EFAULT: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */
+				return -EFAULT;
 			default:
 				pr_warn_once("%s: unhandled return value: %ld\n",
 					     __func__, pages);
-- 
2.31.1



             reply	other threads:[~2021-07-26 15:50 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-26 15:49 David Hildenbrand [this message]
2021-07-30 12:23 ` David Hildenbrand

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210726154932.102880-1-david@redhat.com \
    --to=david@redhat.com \
    --cc=James.Bottomley@HansenPartnership.com \
    --cc=aarcange@redhat.com \
    --cc=arnd@arndb.de \
    --cc=chris@zankel.net \
    --cc=dave.hansen@intel.com \
    --cc=deller@gmx.de \
    --cc=eike-kernel@sf-tec.de \
    --cc=hughd@google.com \
    --cc=ink@jurassic.park.msu.ru \
    --cc=jannh@google.com \
    --cc=jcmvbkbc@gmail.com \
    --cc=jgg@ziepe.ca \
    --cc=kirill.shutemov@linux.intel.com \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linuxram@us.ibm.com \
    --cc=mattst88@gmail.com \
    --cc=mhocko@suse.com \
    --cc=mike.kravetz@oracle.com \
    --cc=minchan@kernel.org \
    --cc=mst@redhat.com \
    --cc=osalvador@suse.de \
    --cc=peterx@redhat.com \
    --cc=riel@surriel.com \
    --cc=rth@twiddle.net \
    --cc=shuah@kernel.org \
    --cc=tsbogend@alpha.franken.de \
    --cc=vbabka@suse.cz \
    --cc=willy@infradead.org \
    --subject='Re: [PATCH v1] mm/madvise: report SIGBUS as -EFAULT for MADV_POPULATE_(READ|WRITE)' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).