On Thu, 6 Jun 2019 00:48:13 +1000 Nicholas Piggin <[email protected]> wrote:
> The kernel currently clamps large system hashes to MAX_ORDER when > hashdist is not set, which is rather arbitrary. > > vmalloc space is limited on 32-bit machines, but this shouldn't > result in much more used because of small physical memory limiting > system hash sizes. > > Include "vmalloc" or "linear" in the kernel log message. > > Signed-off-by: Nicholas Piggin <[email protected]> > --- > > This is a better solution than the previous one for the case of !NUMA > systems running on CONFIG_NUMA kernels, we can clear the default > hashdist early and have everything allocated out of the linear map. > > The hugepage vmap series I will post later, but it's quite > independent from this improvement. > > ... > > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7966,6 +7966,7 @@ void *__init alloc_large_system_hash(const char > *tablename, > unsigned long log2qty, size; > void *table = NULL; > gfp_t gfp_flags; > + bool virt; > > /* allow the kernel cmdline to have a say */ > if (!numentries) { > @@ -8022,6 +8023,7 @@ void *__init alloc_large_system_hash(const char > *tablename, > > gfp_flags = (flags & HASH_ZERO) ? GFP_ATOMIC | __GFP_ZERO : GFP_ATOMIC; > do { > + virt = false; > size = bucketsize << log2qty; > if (flags & HASH_EARLY) { > if (flags & HASH_ZERO) > @@ -8029,26 +8031,26 @@ void *__init alloc_large_system_hash(const char > *tablename, > else > table = memblock_alloc_raw(size, > SMP_CACHE_BYTES); > - } else if (hashdist) { > + } else if (get_order(size) >= MAX_ORDER || hashdist) { > table = __vmalloc(size, gfp_flags, PAGE_KERNEL); > + virt = true; > } else { > /* > * If bucketsize is not a power-of-two, we may free > * some pages at the end of hash table which > * alloc_pages_exact() automatically does > */ > - if (get_order(size) < MAX_ORDER) { > - table = alloc_pages_exact(size, gfp_flags); > - kmemleak_alloc(table, size, 1, gfp_flags); > - } > + table = alloc_pages_exact(size, gfp_flags); > + kmemleak_alloc(table, size, 1, gfp_flags); > } > } while (!table && size > PAGE_SIZE && --log2qty); > > if (!table) > panic("Failed to allocate %s hash table\n", tablename); > > - pr_info("%s hash table entries: %ld (order: %d, %lu bytes)\n", > - tablename, 1UL << log2qty, ilog2(size) - PAGE_SHIFT, size); > + pr_info("%s hash table entries: %ld (order: %d, %lu bytes, %s)\n", > + tablename, 1UL << log2qty, ilog2(size) - PAGE_SHIFT, size, > + virt ? "vmalloc" : "linear"); Could remove `bool virt' and use is_vmalloc_addr() in the printk?
