Date: Wed, 21 Oct 2020 18:18:50 +0300 From: Nick Kostirya <nikolay.kostirya@i11.co> To: freebsd-stable@freebsd.org Subject: Re: mmap and MAP_STACK Message-ID: <20201021181850.49126cdf@i11.co> In-Reply-To: <20201021141657.GJ2643@kib.kiev.ua> References: <20201021165311.186bd606@i11.co> <20201021141657.GJ2643@kib.kiev.ua>
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On Wed, 21 Oct 2020 17:16:57 +0300
Konstantin Belousov <kostikbel@gmail.com> wrote:
> 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.
kdump with MAP_STACK.
87183 polyimport CALL mmap(0,0x1000,0x3<PROT_READ|PROT_WRITE>,0x1402<MAP_PRIVATE|MAP_STACK|MAP_ANON>,0xffffffff,0,0)
87183 polyimport RET mmap -1 errno 22 Invalid argument
kdump without MAP_STACK.
93712 polyimport CALL mmap(0,0x1000,0x3<PROT_READ|PROT_WRITE>,0x1002<MAP_PRIVATE|MAP_ANON>,0xffffffff,0,0)
93712 polyimport RET mmap 547053568/0x209b6000
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