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From: Rik van Riel <>
To: Linus Torvalds <>
Cc: Alan Cox <>,
Subject: [PATCH] saner limit for max_threads
Date: Sun, 17 Jun 2001 23:11:33 -0300 (BRST)	[thread overview]
Message-ID: <Pine.LNX.4.21.0106172308240.2056-100000@imladris.rielhome.conectiva> (raw)


by default the limit for max_threads is such that
the system will try to allocate up to half the
physical memory in task_structs.

Because for each 8kB task struct we'll often want
a struct_mm, a page directory, 3 page tables and
some more structures, this means that a fork bomb
will leave the box DEAD with root never ever getting
a chance of using his reserved tasks and killing the
bad user.

The patch below adjusts the max_threads calculation
to something which should be more sane, though quite
possibly still to high...

Please apply for the next -pre kernel.



--- linux-2.4.6-pre3/kernel/fork.c.orig	Sun Jun 17 20:45:54 2001
+++ linux-2.4.6-pre3/kernel/fork.c	Sun Jun 17 23:07:20 2001
@@ -70,7 +70,7 @@
 	 * value: the thread structures can take up at most half
 	 * of memory.
-	max_threads = mempages / (THREAD_SIZE/PAGE_SIZE) / 2;
+	max_threads = mempages / (THREAD_SIZE/PAGE_SIZE) / 16;
 	init_task.rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
 	init_task.rlim[RLIMIT_NPROC].rlim_max = max_threads/2;

                 reply	other threads:[~2001-06-18  2:12 UTC|newest]

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