Message-ID: <43291CCF.4010902@ccoss.com.cn>
Date: Thu, 15 Sep 2005 15:03:43 +0800
From: "liyu@WAN" <liyu@ccoss.com.cn>
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To: linux-kernel@vger.kernel.org
Subject: Re: Question about page allocation failure
References: <432914F1.4090001@rentalia.com>
In-Reply-To: <432914F1.4090001@rentalia.com>
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the related code is here:

        /* This allocation should allow future memory freeing. */
 
        if (((p->flags & PF_MEMALLOC) || 
unlikely(test_thread_flag(TIF_MEMDIE)))
                        && !in_interrupt()) {
                if (!(gfp_mask & __GFP_NOMEMALLOC)) {
                        /* go through the zonelist yet again, ignoring 
mins */
                        for (i = 0; (z = zones[i]) != NULL; i++) {
                                if (!cpuset_zone_allowed(z))
                                        continue;
                                page = buffered_rmqueue(z, order, gfp_mask);
                                if (page)
                                        goto got_pg;
                        }
                }
                goto nopage;
        }
 
        /* Atomic allocations - we can't balance anything */
        if (!wait)
                goto nopage;
                                                                                                    

nopage:
        if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit()) {
                printk(KERN_WARNING "%s: page allocation failure."
                        " order:%d, mode:0x%x\n",
                        p->comm, order, gfp_mask);
                dump_stack();
        }
        return NULL;


if we are in normal case, there have two possbiles:
    1. total of memory  is too low.
    2. /* Atomic allocations - we can't balance anything */

I think this is not too dangerous.

PS: I use 2.6.12.

Any more clear idea?


sailor


nopage:
   
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