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Message-ID: <CAJuCfpHVgfTMTSNyvGmufjkOLPoz5onw8LujXmA-wZS9nwEikQ@mail.gmail.com>
Date: Tue, 29 Oct 2024 13:03:51 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: Mike Rapoport <rppt@...nel.org>
Cc: akpm@...ux-foundation.org, arnd@...nel.org, arnd@...db.de,
pasha.tatashin@...een.com, mcgrof@...nel.org, song@...nel.org,
mhiramat@...nel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
kernel test robot <lkp@...el.com>
Subject: Re: [PATCH 1/1] alloc_tag: avoid execmem_vmap() when !MMU
On Tue, Oct 29, 2024 at 10:13 AM Mike Rapoport <rppt@...nel.org> wrote:
>
> Hi Suren,
>
> On Mon, Oct 28, 2024 at 01:29:35PM -0700, Suren Baghdasaryan wrote:
> > With CONFIG_MMU=n __get_vm_area_node() is not available and memory for the
> > allocation tags cannot be populated as needed. For this case, populate the
> > required memory at initialization time.
>
> Do we care that much to have alloc_tags on !MMU configs?
>
> Your patch is great, but it would have been a lot easier to make
> MEM_ALLOC_PROFILING depend on MMU.
I didn't want to prevent !MMU users from using allocation profiling
but I'm not aware of any current !MMU users. Therefore I have no
objections to making MEM_ALLOC_PROFILING dependent on MMU if we indeed
don't care about !MMU && MEM_ALLOC_PROFILING configuration.
I'll be posting v5 tomorrow with all these fixes, so please let me
know which way you prefer. Thanks!
>
> > Fixes: 57bc3834fb6f ("alloc_tag: populate memory for module tags as needed")
> > Reported-by: kernel test robot <lkp@...el.com>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202410250808.dQGyYjlk-lkp@intel.com/
> > Closes: https://lore.kernel.org/oe-lkp/202410251525.9f85854d-oliver.sang@intel.com
> > Closes: https://lore.kernel.org/oe-kbuild-all/202410261016.IO7C6Cml-lkp@intel.com/
> > Closes: https://lore.kernel.org/oe-kbuild-all/202410270919.LebQlmxD-lkp@intel.com/
> > Cc: Arnd Bergmann <arnd@...db.de>
> > Cc: Mike Rapoport (Microsoft) <rppt@...nel.org>
> > Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
> > ---
> > include/linux/execmem.h | 2 ++
> > lib/alloc_tag.c | 23 ++++++++++++++++++++++-
> > mm/execmem.c | 32 ++++++++++++++++----------------
> > 3 files changed, 40 insertions(+), 17 deletions(-)
> >
> > diff --git a/include/linux/execmem.h b/include/linux/execmem.h
> > index 5a5e2917f870..64130ae19690 100644
> > --- a/include/linux/execmem.h
> > +++ b/include/linux/execmem.h
> > @@ -139,6 +139,7 @@ void *execmem_alloc(enum execmem_type type, size_t size);
> > */
> > void execmem_free(void *ptr);
> >
> > +#ifdef CONFIG_MMU
> > /**
> > * execmem_vmap - create virtual mapping for EXECMEM_MODULE_DATA memory
> > * @size: size of the virtual mapping in bytes
> > @@ -148,6 +149,7 @@ void execmem_free(void *ptr);
> > * Return: the area descriptor on success or %NULL on failure.
> > */
> > struct vm_struct *execmem_vmap(size_t size);
> > +#endif
> >
> > /**
> > * execmem_update_copy - copy an update to executable memory
> > diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> > index c1ddac2d29f0..1c74942e6dfd 100644
> > --- a/lib/alloc_tag.c
> > +++ b/lib/alloc_tag.c
> > @@ -268,7 +268,6 @@ void __init alloc_tag_sec_init(void)
> > #ifdef CONFIG_MODULES
> >
> > static struct maple_tree mod_area_mt = MTREE_INIT(mod_area_mt, MT_FLAGS_ALLOC_RANGE);
> > -static struct vm_struct *vm_module_tags;
> > /* A dummy object used to indicate an unloaded module */
> > static struct module unloaded_mod;
> > /* A dummy object used to indicate a module prepended area */
> > @@ -391,6 +390,9 @@ static bool find_aligned_area(struct ma_state *mas, unsigned long section_size,
> > return false;
> > }
> >
> > +#ifdef CONFIG_MMU
> > +static struct vm_struct *vm_module_tags;
> > +
> > static int vm_module_tags_populate(void)
> > {
> > unsigned long phys_size = vm_module_tags->nr_pages << PAGE_SHIFT;
> > @@ -417,6 +419,13 @@ static int vm_module_tags_populate(void)
> >
> > return 0;
> > }
> > +#else
> > +static int vm_module_tags_populate(void)
> > +{
> > + /* Memory was already allocated */
> > + return 0;
> > +}
> > +#endif
> >
> > static void *reserve_module_tags(struct module *mod, unsigned long size,
> > unsigned int prepend, unsigned long align)
> > @@ -561,6 +570,7 @@ static void replace_module(struct module *mod, struct module *new_mod)
> >
> > static int __init alloc_mod_tags_mem(void)
> > {
> > +#ifdef CONFIG_MMU
> > /* Map space to copy allocation tags */
> > vm_module_tags = execmem_vmap(MODULE_ALLOC_TAG_VMAP_SIZE);
> > if (!vm_module_tags) {
> > @@ -578,6 +588,13 @@ static int __init alloc_mod_tags_mem(void)
> > }
> >
> > module_tags.start_addr = (unsigned long)vm_module_tags->addr;
> > +#else
> > + /* Allocate space to copy allocation tags */
> > + module_tags.start_addr = (unsigned long)execmem_alloc(EXECMEM_MODULE_DATA,
> > + MODULE_ALLOC_TAG_VMAP_SIZE);
> > + if (!module_tags.start_addr)
> > + return -ENOMEM;
> > +#endif
> > module_tags.end_addr = module_tags.start_addr + MODULE_ALLOC_TAG_VMAP_SIZE;
> > /* Ensure the base is alloc_tag aligned when required for indexing */
> > module_tags.start_addr = alloc_tag_align(module_tags.start_addr);
> > @@ -587,6 +604,7 @@ static int __init alloc_mod_tags_mem(void)
> >
> > static void __init free_mod_tags_mem(void)
> > {
> > +#ifdef CONFIG_MMU
> > int i;
> >
> > module_tags.start_addr = 0;
> > @@ -594,6 +612,9 @@ static void __init free_mod_tags_mem(void)
> > __free_page(vm_module_tags->pages[i]);
> > kfree(vm_module_tags->pages);
> > free_vm_area(vm_module_tags);
> > +#else
> > + execmem_free((void *)module_tags.start_addr);
> > +#endif
> > }
> >
> > #else /* CONFIG_MODULES */
> > diff --git a/mm/execmem.c b/mm/execmem.c
> > index 5c0f9f2d6f83..317b6a8d35be 100644
> > --- a/mm/execmem.c
> > +++ b/mm/execmem.c
> > @@ -64,6 +64,22 @@ static void *execmem_vmalloc(struct execmem_range *range, size_t size,
> >
> > return p;
> > }
> > +
> > +struct vm_struct *execmem_vmap(size_t size)
> > +{
> > + struct execmem_range *range = &execmem_info->ranges[EXECMEM_MODULE_DATA];
> > + struct vm_struct *area;
> > +
> > + area = __get_vm_area_node(size, range->alignment, PAGE_SHIFT, VM_ALLOC,
> > + range->start, range->end, NUMA_NO_NODE,
> > + GFP_KERNEL, __builtin_return_address(0));
> > + if (!area && range->fallback_start)
> > + area = __get_vm_area_node(size, range->alignment, PAGE_SHIFT, VM_ALLOC,
> > + range->fallback_start, range->fallback_end,
> > + NUMA_NO_NODE, GFP_KERNEL, __builtin_return_address(0));
> > +
> > + return area;
> > +}
> > #else
> > static void *execmem_vmalloc(struct execmem_range *range, size_t size,
> > pgprot_t pgprot, unsigned long vm_flags)
> > @@ -368,22 +384,6 @@ void execmem_free(void *ptr)
> > vfree(ptr);
> > }
> >
> > -struct vm_struct *execmem_vmap(size_t size)
> > -{
> > - struct execmem_range *range = &execmem_info->ranges[EXECMEM_MODULE_DATA];
> > - struct vm_struct *area;
> > -
> > - area = __get_vm_area_node(size, range->alignment, PAGE_SHIFT, VM_ALLOC,
> > - range->start, range->end, NUMA_NO_NODE,
> > - GFP_KERNEL, __builtin_return_address(0));
> > - if (!area && range->fallback_start)
> > - area = __get_vm_area_node(size, range->alignment, PAGE_SHIFT, VM_ALLOC,
> > - range->fallback_start, range->fallback_end,
> > - NUMA_NO_NODE, GFP_KERNEL, __builtin_return_address(0));
> > -
> > - return area;
> > -}
> > -
> > void *execmem_update_copy(void *dst, const void *src, size_t size)
> > {
> > return text_poke_copy(dst, src, size);
> >
> > base-commit: 92409df3e00a17d6fd5bb27732fa186749725ed5
> > --
> > 2.47.0.163.g1226f6d8fa-goog
> >
>
> --
> Sincerely yours,
> Mike.
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