From: Andrew Morton <akpm@linux-foundation.org>
To: aarcange@redhat.com, akpm@linux-foundation.org, arnd@arndb.de,
chris@zankel.net, dave.hansen@intel.com, david@redhat.com,
deller@gmx.de, eike-kernel@sf-tec.de, hughd@google.com,
ink@jurassic.park.msu.ru, James.Bottomley@HansenPartnership.com,
jannh@google.com, jcmvbkbc@gmail.com, jgg@ziepe.ca,
kirill.shutemov@linux.intel.com, linux-mm@kvack.org,
linuxram@us.ibm.com, mattst88@gmail.com, mhocko@suse.com,
mike.kravetz@oracle.com, minchan@kernel.org,
mm-commits@vger.kernel.org, mst@redhat.com, osalvador@suse.de,
peterx@redhat.com, riel@surriel.com, rth@twiddle.net,
shuah@kernel.org, torvalds@linux-foundation.org,
tsbogend@alpha.franken.de, vbabka@suse.cz, willy@infradead.org
Subject: [patch 5/7] mm/madvise: report SIGBUS as -EFAULT for MADV_POPULATE_(READ|WRITE)
Date: Fri, 13 Aug 2021 16:54:37 -0700 [thread overview]
Message-ID: <20210813235437.jpdoEJdjF%akpm@linux-foundation.org> (raw)
In-Reply-To: <20210813165350.dc9afa56d27eadbd8ce629c0@linux-foundation.org>
From: David Hildenbrand <david@redhat.com>
Subject: mm/madvise: report SIGBUS as -EFAULT for MADV_POPULATE_(READ|WRITE)
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 behavio= r.
Link: https://lkml.kernel.org/r/20210726154932.102880-1-david@redhat.com
Fixes: 4ca9b3859dac ("mm/madvise: introduce MADV_POPULATE_(READ|WRITE) to prefault page tables")
Signed-off-by: David Hildenbrand <david@redhat.com>
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: Andrew Morton <akpm@linux-foundation.org>
---
mm/gup.c | 7 +++++--
mm/madvise.c | 4 +++-
2 files changed, 8 insertions(+), 3 deletions(-)
--- a/mm/gup.c~mm-madvise-report-sigbus-as-efault-for-madv_populate_readwrite
+++ a/mm/gup.c
@@ -1558,9 +1558,12 @@ long faultin_vma_page_range(struct vm_ar
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);
}
--- a/mm/madvise.c~mm-madvise-report-sigbus-as-efault-for-madv_populate_readwrite
+++ a/mm/madvise.c
@@ -862,10 +862,12 @@ static long madvise_populate(struct vm_a
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);
_
next prev parent reply other threads:[~2021-08-13 23:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-13 23:53 incoming Andrew Morton
2021-08-13 23:54 ` [patch 1/7] kasan, kmemleak: reset tags when scanning block Andrew Morton
2021-08-13 23:54 ` [patch 2/7] kasan, slub: reset tag when printing address Andrew Morton
2021-08-13 23:54 ` [patch 3/7] slub: fix kmalloc_pagealloc_invalid_free unit test Andrew Morton
2021-08-13 23:54 ` [patch 4/7] mm: slub: fix slub_debug disabling for list of slabs Andrew Morton
2021-08-13 23:54 ` Andrew Morton [this message]
2021-08-13 23:54 ` [patch 6/7] mm/memcg: fix incorrect flushing of lruvec data in obj_stock Andrew Morton
2021-08-13 23:54 ` [patch 7/7] lib: use PFN_PHYS() in devmem_is_allowed() Andrew Morton
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