Re: [bug] SLOB crash, 2.6.24-rc2

!MAILaRCHIVE_VOTE_RePLACE
Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]
To: David Miller <davem@...>
Cc: <mingo@...>, <rjw@...>, <linux-kernel@...>, <akpm@...>, <torvalds@...>
Date: Wednesday, November 14, 2007 - 7:37 pm

On Wed, Nov 14, 2007 at 03:10:13PM -0800, David Miller wrote:

No, the usual strategy for debugging problems -outside- SLOB is to
switch to another allocator with more extensive debugging facilities.

It is of course possible to add redzoning, last user, etc., but there
aren't many advantages to implementing these in SLOB compared to
switching allocators, unless the bug disappears in those other
allocators. In the case of random pointer fandango, such bugs are
likely to disappear when you turn on debugging anyway.

The most likely thing you'll hit in SLOB vs SLUB/SLAB is that SLOB
doesn't hand back power-of-two allocations for kmalloc. Instead, it
has 2-byte granularity on most machines. So small pointer overruns on
kmalloced objects will be somewhat more visible in SLOB than
SLAB/SLUB. I don't think SLAB/SLUB debugging can detect overruns
inside the not-requested-but-still-allocated region of objects.

I've implemented redzoning and various other debugging checks for
earlier versions of SLOB to find problems -in- the allocator, but
those won't apply to current SLOB (which can be considered v2).

-- 
Mathematics is the supreme nostalgia of our time.
-
Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]

Messages in current thread:
2.6.24-rc2: Reported regressions from 2.6.23 (updated), Rafael J. Wysocki, (Sun Nov 11, 3:58 pm)
[bug] SLOB crash, 2.6.24-rc2, Ingo Molnar, (Wed Nov 14, 7:20 am)
Re: [bug] SLOB crash, 2.6.24-rc2, Matt Mackall, (Wed Nov 14, 1:36 pm)
Re: [bug] SLOB crash, 2.6.24-rc2, Matt Mackall, (Wed Nov 14, 2:39 pm)
Re: [bug] SLOB crash, 2.6.24-rc2, Ingo Molnar, (Wed Nov 14, 3:05 pm)
Re: [bug] SLOB crash, 2.6.24-rc2, David Miller, (Wed Nov 14, 6:39 pm)
Re: [bug] SLOB crash, 2.6.24-rc2, Matt Mackall, (Wed Nov 14, 6:53 pm)
Re: [bug] SLOB crash, 2.6.24-rc2, David Miller, (Wed Nov 14, 7:10 pm)
Re: [bug] SLOB crash, 2.6.24-rc2, Matt Mackall, (Wed Nov 14, 7:37 pm)
Re: [bug] SLOB crash, 2.6.24-rc2, David Miller, (Wed Nov 14, 7:41 pm)
Re: [bug] SLOB crash, 2.6.24-rc2, Ingo Molnar, (Thu Nov 15, 6:43 am)
Re: [bug] SLOB crash, 2.6.24-rc2, Nick Piggin, (Thu Nov 15, 6:57 am)
Re: [bug] SLOB crash, 2.6.24-rc2, Ingo Molnar, (Thu Nov 15, 7:28 am)
Re: [bug] SLOB crash, 2.6.24-rc2, Dave Haywood, (Thu Nov 15, 8:18 am)
Re: [bug] SLOB crash, 2.6.24-rc2, Nick Piggin, (Thu Nov 15, 7:39 am)
[patch] slob: fix memory corruption, Ingo Molnar, (Thu Nov 15, 7:32 am)
Re: [patch] slob: fix memory corruption, Matt Mackall, (Thu Nov 15, 12:00 pm)
Re: [patch] slob: fix memory corruption, Ingo Molnar, (Thu Nov 15, 8:48 am)
Re: [patch] slob: fix memory corruption, Nick Piggin, (Thu Nov 15, 4:25 pm)
Re: [bug] SLOB crash, 2.6.24-rc2, David Miller, (Thu Nov 15, 6:51 am)
Re: [bug] SLOB crash, 2.6.24-rc2, Ingo Molnar, (Thu Nov 15, 7:03 am)
Re: [bug] SLOB crash, 2.6.24-rc2, David Miller, (Thu Nov 15, 7:05 am)
Re: [bug] SLOB crash, 2.6.24-rc2, Matt Mackall, (Wed Nov 14, 8:09 pm)
Re: [bug] SLOB crash, 2.6.24-rc2, Matt Mackall, (Wed Nov 14, 3:42 pm)
Re: 2.6.24-rc2: Reported regressions from 2.6.23 (updated), Francois Romieu, (Sun Nov 11, 4:33 pm)
Re: 2.6.24-rc2: Reported regressions from 2.6.23 (updated), Bartlomiej Zolnierkiewicz..., (Sun Nov 11, 6:22 pm)
Re: 2.6.24-rc2: Reported regressions from 2.6.23 (updated), Thomas Lindroth, (Tue Nov 13, 10:09 am)
Re: 2.6.24-rc2: Reported regressions from 2.6.23 (updated), Rafael J. Wysocki, (Sun Nov 11, 4:34 pm)