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authorDavid Hildenbrand <david@redhat.com>2021-08-13 16:54:37 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-08-13 14:09:31 -1000
commiteb2faa513c246ed47ae34a205928ab663bc5a18f (patch)
tree0cd7f02657f6af9e20faf9c834a9c37eb2c8291b /mm
parenta7f1d48585b34730765dcda09ead6edc4ac16a5c (diff)
downloadlinux-eb2faa513c246ed47ae34a205928ab663bc5a18f.tar.bz2
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 behavior. 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> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/gup.c7
-rw-r--r--mm/madvise.c4
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);