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authorLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-31 09:19:46 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-31 09:19:46 -0700
commit5307cc1aa53850f017c8053db034cf950b670ac9 (patch)
tree6fd2ff3fe382ba1aac5e8b6c703268200a80ed40 /mm/filemap.c
parentbb374b7b938f73666c403b201b3dd48ec9fe118a (diff)
downloadconfigs-5307cc1aa53850f017c8053db034cf950b670ac9.tar.gz
Remove broken ptrace() special-case code from file mapping
The kernel has for random historical reasons allowed ptrace() accesses to access (and insert) pages into the page cache above the size of the file. However, Nick broke that by mistake when doing the new fault handling in commit 54cb8821de07f2ffcd28c380ce9b93d5784b40d7 ("mm: merge populate and nopage into fault (fixes nonlinear)". The breakage caused a hang with gdb when trying to access the invalid page. The ptrace "feature" really isn't worth resurrecting, since it really is wrong both from a portability _and_ from an internal page cache validity standpoint. So this removes those old broken remnants, and fixes the ptrace() hang in the process. Noticed and bisected by Duane Griffin, who also supplied a test-case (quoth Nick: "Well that's probably the best bug report I've ever had, thanks Duane!"). Cc: Duane Griffin <duaneg@dghda.com> Acked-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c13
1 files changed, 2 insertions, 11 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index 9940895f734..188cf5fd3e8 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1300,7 +1300,7 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
if (vmf->pgoff >= size)
- goto outside_data_content;
+ return VM_FAULT_SIGBUS;
/* If we don't want any read-ahead, don't bother */
if (VM_RandomReadHint(vma))
@@ -1377,7 +1377,7 @@ retry_find:
if (unlikely(vmf->pgoff >= size)) {
unlock_page(page);
page_cache_release(page);
- goto outside_data_content;
+ return VM_FAULT_SIGBUS;
}
/*
@@ -1388,15 +1388,6 @@ retry_find:
vmf->page = page;
return ret | VM_FAULT_LOCKED;
-outside_data_content:
- /*
- * An external ptracer can access pages that normally aren't
- * accessible..
- */
- if (vma->vm_mm == current->mm)
- return VM_FAULT_SIGBUS;
-
- /* Fall through to the non-read-ahead case */
no_cached_page:
/*
* We're only likely to ever get here if MADV_RANDOM is in