From: Yang Shi <shy828301@gmail.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: Jiri Slaby <jirislaby@kernel.org>,
Rik van Riel <riel@surriel.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, Matthew Wilcox <willy@infradead.org>,
Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH v2] mm: align larger anonymous mappings on THP boundaries
Date: Wed, 17 Jan 2024 16:15:34 -0800 [thread overview]
Message-ID: <CAHbLzko=pN_5NtU_=aKTMs9c+GHMn0_gKMs5SifQzaR68hD6KQ@mail.gmail.com> (raw)
In-Reply-To: <CAJuCfpF7tK07rGHyWPFSVe=Lwv0_zN-J9WsV+nkhJffY+xdXkw@mail.gmail.com>
On Wed, Jan 17, 2024 at 4:11 PM Suren Baghdasaryan <surenb@google.com> wrote:
>
> On Wed, Jan 17, 2024 at 4:09 PM Suren Baghdasaryan <surenb@google.com> wrote:
> >
> > On Wed, Jan 17, 2024 at 4:07 PM Yang Shi <shy828301@gmail.com> wrote:
> > >
> > > On Tue, Jan 16, 2024 at 4:09 AM Jiri Slaby <jirislaby@kernel.org> wrote:
> > > >
> > > > On 16. 01. 24, 12:53, Jiri Slaby wrote:
> > > > > Hi,
> > > > >
> > > > > On 09. 08. 22, 20:24, Rik van Riel wrote:
> > > > >> Align larger anonymous memory mappings on THP boundaries by
> > > > >> going through thp_get_unmapped_area if THPs are enabled for
> > > > >> the current process.
> > > > >>
> > > > >> With this patch, larger anonymous mappings are now THP aligned.
> > > > >> When a malloc library allocates a 2MB or larger arena, that
> > > > >> arena can now be mapped with THPs right from the start, which
> > > > >> can result in better TLB hit rates and execution time.
> > > > >
> > > > > This appears to break 32bit processes on x86_64 (at least). In
> > > > > particular, 32bit kernel or firefox builds in our build system.
> > > > >
> > > > > Reverting this on top of 6.7 makes it work again.
> > > > >
> > > > > Downstream report:
> > > > > https://bugzilla.suse.com/show_bug.cgi?id=1218841
> > > > >
> > > > > So running:
> > > > > pahole -J --btf_gen_floats -j --lang_exclude=rust
> > > > > --skip_encoding_btf_inconsistent_proto --btf_gen_optimized .tmp_vmlinux.btf
> > > > >
> > > > > crashes or errors out with some random errors:
> > > > > [182671] STRUCT idr's field 'idr_next' offset=128 bit_size=0 type=181346
> > > > > Error emitting field
> > > > >
> > > > > strace shows mmap() fails with ENOMEM right before the errors:
> > > > > 1223 mmap2(NULL, 5783552, PROT_READ|PROT_WRITE,
> > > > > MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 <unfinished ...>
> > > > > ...
> > > > > 1223 <... mmap2 resumed>) = -1 ENOMEM (Cannot allocate
> > > > > memory)
> > > > >
> > > > > Note the .tmp_vmlinux.btf above can be arbitrary, but likely large
> > > > > enough. For reference, one is available at:
> > > > > https://decibel.fi.muni.cz/~xslaby/n/btf
> > > > >
> > > > > Any ideas?
> > > >
> > > > This works around the problem, of course (but is a band-aid, not a fix):
> > > >
> > > > --- a/mm/mmap.c
> > > > +++ b/mm/mmap.c
> > > > @@ -1829,7 +1829,7 @@ get_unmapped_area(struct file *file, unsigned long
> > > > addr, unsigned long len,
> > > > */
> > > > pgoff = 0;
> > > > get_area = shmem_get_unmapped_area;
> > > > - } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
> > > > + } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
> > > > !in_32bit_syscall()) {
> > > > /* Ensures that larger anonymous mappings are THP
> > > > aligned. */
> > > > get_area = thp_get_unmapped_area;
> > > > }
> > > >
> > > >
> > > > thp_get_unmapped_area() does not take care of the legacy stuff...
> > >
> > > Could you please help test the below patch? It is compiled, but I
> > > don't have 32 bit userspace or machine to test it.
> >
> > Hmm. I think you misunderstood me. This is happening on x86_64 emulated system.
>
> I mean it's x86_64 Android emulator, so kernel is 64bit.
No, I didn't. This patch is aimed to solve the -ENOMEM problem
reported by Jiri Slaby. I believe his test was run on 32 bit machine
or 32 bit userspace on 64 bit kernel.
>
> >
> > >
> > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > > index 94ef5c02b459..a4d0839e5f31 100644
> > > --- a/mm/huge_memory.c
> > > +++ b/mm/huge_memory.c
> > > @@ -811,6 +811,9 @@ static unsigned long
> > > __thp_get_unmapped_area(struct file *filp,
> > > loff_t off_align = round_up(off, size);
> > > unsigned long len_pad, ret;
> > >
> > > + if (IS_ENABLED(CONFIG_32BIT) || in_compat_syscall())
> > > + return 0;
> > > +
> > > if (off_end <= off_align || (off_end - off_align) < size)
> > > return 0;
> > >
> > >
> > > >
> > > > regards,
> > > > --
> > > > js
> > > > suse labs
> > > >
> > >
next prev parent reply other threads:[~2024-01-18 0:15 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-09 18:24 [PATCH v2] mm: align larger anonymous mappings on THP boundaries Rik van Riel
2022-08-10 17:06 ` Yang Shi
2024-01-16 11:53 ` Jiri Slaby
2024-01-16 12:09 ` Jiri Slaby
2024-01-16 19:16 ` Suren Baghdasaryan
2024-01-16 20:56 ` Yang Shi
2024-01-16 21:57 ` Suren Baghdasaryan
2024-01-16 22:25 ` Yang Shi
2024-01-16 22:30 ` Suren Baghdasaryan
2024-01-16 23:14 ` Yang Shi
2024-01-17 17:40 ` Kees Cook
2024-01-17 23:32 ` Yang Shi
2024-01-18 0:01 ` Suren Baghdasaryan
2024-01-18 0:13 ` Yang Shi
2024-01-18 0:29 ` Suren Baghdasaryan
2024-01-18 1:34 ` Suren Baghdasaryan
2024-01-18 2:10 ` Suren Baghdasaryan
2024-01-16 20:55 ` Yang Shi
2024-01-18 0:07 ` Yang Shi
2024-01-18 0:09 ` Suren Baghdasaryan
2024-01-18 0:11 ` Suren Baghdasaryan
2024-01-18 0:15 ` Yang Shi [this message]
2024-01-18 0:28 ` Suren Baghdasaryan
2024-01-18 7:04 ` Jiri Slaby
2024-01-18 17:48 ` Suren Baghdasaryan
2024-01-18 18:42 ` Yang Shi
2024-01-18 18:42 ` Yang Shi
2024-01-20 13:43 ` Linux regression tracking #adding (Thorsten Leemhuis)
2024-01-20 15:47 ` Linux regression tracking #adding (Thorsten Leemhuis)
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