The patch titled
Potential fix for fdtable badness
has been removed from the -mm tree. Its filename was
fdtable-implement-new-pagesize-based-fdtable-allocator-fix.patch
This patch was dropped because it was folded into fdtable-implement-new-pagesize-based-fdtable-allocator.patch
------------------------------------------------------
Subject: Potential fix for fdtable badness
From: Vadim Lobanov <vlobanov@xxxxxxxxxxxxx>
Fix the computation of the length of an allocated fdarray, when we decide to
grow the fdtable. The rationale behind this fix is as follows:
=> The 'nr' variable is the requested fd, so will be one less than the minimum
allowable fdarray size.
=> Due to the above fact, when we divide 'nr' by a fourth-of-a-page block, we
will always be exactly one block short of the size we need.
=> Incrementing before the division is wrong, because the division will discard
a non-zero modulo, possibly leaving us one fourth-of-a-page block short.
Signed-off-by: Vadim Lobanov <vlobanov@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/file.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff -puN fs/file.c~fdtable-implement-new-pagesize-based-fdtable-allocator-fix fs/file.c
--- a/fs/file.c~fdtable-implement-new-pagesize-based-fdtable-allocator-fix
+++ a/fs/file.c
@@ -144,9 +144,8 @@ static struct fdtable * alloc_fdtable(un
* the fdarray into page-sized chunks: starting at a quarter of a page,
* and growing in powers of two from there on.
*/
- nr++;
nr /= (PAGE_SIZE / 4 / sizeof(struct file *));
- nr = roundup_pow_of_two(nr);
+ nr = roundup_pow_of_two(nr + 1);
nr *= (PAGE_SIZE / 4 / sizeof(struct file *));
if (nr > NR_OPEN)
nr = NR_OPEN;
_
Patches currently in -mm which might be from vlobanov@xxxxxxxxxxxxx are
fdtable-delete-pointless-code-in-dup_fd.patch
fdtable-make-fdarray-and-fdsets-equal-in-size.patch
fdtable-remove-the-free_files-field.patch
fdtable-implement-new-pagesize-based-fdtable-allocator.patch
fdtable-implement-new-pagesize-based-fdtable-allocator-fix.patch
fdtable-implement-new-pagesize-based-fdtable-allocator-bound-minimum-allocation-size.patch
fdtable-implement-new-pagesize-based-fdtable-allocator-avoid-fdset-cacheline-ping-pong.patch
fdtable-make-fdarray-and-fdsets-equal-in-size-slim.patch
-
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