I am resending this mail because the linux-kernel list was not CCed. On 16.02.2015 19:23, Guenter Roeck wrote: > On Mon, Feb 16, 2015 at 07:00:44PM +0100, Heinrich Schuchardt wrote: >> PAGE_SIZE is not guaranteed to be equal to or less than 8 times the >> THREAD_SIZE. >> >> E.g. architecture hexagon may have page size 1M and thread size 4096. >> >> This would lead to a division by zero. >> >> Signed-off-by: Heinrich Schuchardt <xypron.g...@gmx.de> >> --- >> kernel/fork.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/fork.c b/kernel/fork.c >> index cf65139..71e2583 100644 >> --- a/kernel/fork.c >> +++ b/kernel/fork.c >> @@ -273,7 +273,8 @@ void __init fork_init(unsigned long mempages) >> * value: the thread structures can take up at most half >> * of memory. >> */ >> - max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); >> + max_threads = (u64) PAGE_SIZE * (u64) mempages >> + / (u64) THREAD_SIZE / 8UL; > > How about > max_threads = mempages / (8 * THREAD_SIZE) * PAGE_SIZE; > > instead ? That would avoid the u64.
We have to consider the case mempages < 8 * THREAD_SIZE. Let mempages = 1024 THREAD_SIZE = 4096 PAGE_SIZE = 1M Your code gives 0. Mine gives 8192. Best regards Heinrich -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
