linux-4.4.1/__alloc_pages_nodemask() の履歴(No.1)

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linux-4.4.1/__alloc_pages_nodemask() へ行く。
- 1 (2016-03-10 (木) 10:05:05)
- 2 (2016-03-10 (木) 10:06:03)
- 3 (2016-03-14 (月) 11:15:56)

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パス: linux-4.4.1/mm/page_alloc.c

FIXME: これは何？
- 説明

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実装†

/*
 * This is the 'heart' of the zoned buddy allocator.
 */
struct page *
__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
                        struct zonelist *zonelist, nodemask_t *nodemask)
{
        struct zoneref *preferred_zoneref;
        struct page *page = NULL;
        unsigned int cpuset_mems_cookie;
        int alloc_flags = ALLOC_WMARK_LOW|ALLOC_CPUSET|ALLOC_FAIR;
        gfp_t alloc_mask; /* The gfp_t that was actually used for allocation */
        struct alloc_context ac = {
                .high_zoneidx = gfp_zone(gfp_mask),
                .nodemask = nodemask,
                .migratetype = gfpflags_to_migratetype(gfp_mask),
        };

        gfp_mask &= gfp_allowed_mask;

- linux-4.4.1/gfp_allowed_mask(global)

        lockdep_trace_alloc(gfp_mask);

        might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);

- linux-4.4.1/lockdep_trace_alloc()
- linux-4.4.1/might_sleep_if()

        if (should_fail_alloc_page(gfp_mask, order))
                return NULL;

- linux-4.4.1/should_fail_alloc_page()

        /*
         * Check the zones suitable for the gfp_mask contain at least one
         * valid zone. It's possible to have an empty zonelist as a result
         * of __GFP_THISNODE and a memoryless node
         */
        if (unlikely(!zonelist->_zonerefs->zone))
                return NULL;

        if (IS_ENABLED(CONFIG_CMA) && ac.migratetype == MIGRATE_MOVABLE)
                alloc_flags |= ALLOC_CMA;

retry_cpuset:
        cpuset_mems_cookie = read_mems_allowed_begin();

- linux-4.4.1/read_mems_allowed_begin()

        /* We set it here, as __alloc_pages_slowpath might have changed it */
        ac.zonelist = zonelist;

        /* Dirty zone balancing only done in the fast path */
        ac.spread_dirty_pages = (gfp_mask & __GFP_WRITE);

        /* The preferred zone is used for statistics later */
        preferred_zoneref = first_zones_zonelist(ac.zonelist, ac.high_zoneidx,
                                ac.nodemask ? : &cpuset_current_mems_allowed,
                                &ac.preferred_zone);
        if (!ac.preferred_zone)
                goto out;
        ac.classzone_idx = zonelist_zone_idx(preferred_zoneref);

        /* First allocation attempt */
        alloc_mask = gfp_mask|__GFP_HARDWALL;
        page = get_page_from_freelist(alloc_mask, order, alloc_flags, &ac);

- linux-4.4.1/get_page_from_freelist()

        if (unlikely(!page)) {
                /*
                 * Runtime PM, block IO and its error handling path
                 * can deadlock because I/O on the device might not
                 * complete.
                 */
                alloc_mask = memalloc_noio_flags(gfp_mask);
                ac.spread_dirty_pages = false;

                page = __alloc_pages_slowpath(alloc_mask, order, &ac);
        }

- linux-4.4.1/memalloc_noio_flags()
- linux-4.4.1/__alloc_pages_slowpath()

        if (kmemcheck_enabled && page)
                kmemcheck_pagealloc_alloc(page, order, gfp_mask);

- linux-4.4.1/kmemcheck_pagealloc_alloc()

        trace_mm_page_alloc(page, order, alloc_mask, ac.migratetype);

- linux-4.4.1/trace_mm_page_alloc()

out:
        /*
         * When updating a task's mems_allowed, it is possible to race with
         * parallel threads in such a way that an allocation can fail while
         * the mask is being updated. If a page allocation is about to fail,
         * check if the cpuset changed during allocation and if so, retry.
         */
        if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
                goto retry_cpuset;

- linux-4.4.1/read_mems_allowed_retry()

        return page;
}
EXPORT_SYMBOL(__alloc_pages_nodemask);

- linux-4.4.1/__alloc_pages_nodemask()

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linux-4.4.1/__alloc_pages_nodemask() の履歴(No.1)

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