Re: stress test for parallel workers

On Wed, Dec 11, 2019 at 3:22 PM Thomas Munro <thomas.munro@gmail.com> wrote:
> On Tue, Oct 15, 2019 at 4:50 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > > Filed at
> > > https://bugzilla.kernel.org/show_bug.cgi?id=205183
>
> For the curious-and-not-subscribed, there's now a kernel patch
> proposed for this.  We guessed pretty close, but the problem wasn't
> those dodgy looking magic numbers, it was that the bad stack expansion
> check only allows for user space to expand the stack
> (FAULT_FLAG_USER), and here the kernel itself wants to build a stack
> frame.

Hehe, the dodgy looking magic numbers *were* wrong:

- * The kernel signal delivery code writes up to about 1.5kB
+ * The kernel signal delivery code writes a bit over 4KB

https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20200724092528.1578671-2-mpe@ellerman.id.au/