Date: Wed, 21 Oct 2020 17:16:57 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Nick Kostirya <nikolay.kostirya@i11.co> Cc: freebsd-stable@freebsd.org Subject: Re: mmap and MAP_STACK Message-ID: <20201021141657.GJ2643@kib.kiev.ua> In-Reply-To: <20201021165311.186bd606@i11.co> References: <20201021165311.186bd606@i11.co>
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On Wed, Oct 21, 2020 at 04:53:11PM +0300, Nick Kostirya via freebsd-stable wrote:
> Hello.
> I have question about mmap.
>
> void *OSMem::AllocateDataArea(size_t &space)
> {
> // Round up to an integral number of pages.
> space = (space + pageSize-1) & ~(pageSize-1);
> int fd = -1; // This value is required by FreeBSD. Linux doesn't care
> int flags = MAP_PRIVATE | MAP_ANON;
> #ifdef MAP_STACK
> if (memUsage == UsageStack) flags |= MAP_STACK; // OpenBSD seems to require this
> #endif
> void *result = mmap(0, space, PROT_READ|PROT_WRITE, flags, fd, 0);
> // Convert MAP_FAILED (-1) into NULL
> if (result == MAP_FAILED)
> return 0;
> return result;
> }
>
>
> When MAP_STACK is used, "insufficient memory" error occurs.
> When MAP_STACK removed, it is all right.
>
> Please tell me why.
Show ktrace/kdump output of the mmap(2) without and with MAP_STACK.
Or provide a minimal self-contained C source that demonstrates your
issue.
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