First, there were no serfs in 1917, since all serfs had been emancipated in 1861. So the question is technically about peasants rather than serfs.

The answer (surprise!) is that it's complicated. Even after steady urbanization and industrialization starting in the 1890s, the Russian Empire was still very rural and agricultural in 1917 - something like 80% of the population were peasants, although in fairness this obscures the fact that lots of these peasants in this period were working seasonally in cities, or working on craft industries in their villages.

The peasants in 1917 had gripes - serious ones. A major one is that although they were no longer serfs, they in effect had to pay for their emancipation in so-called Redemption Payments. In essence this meant that freed peasants received allotments of land that they had to pay for, plus interest, and that often this was smaller and worse land than they had actually worked prior to 1861. After 1905 and the revolution that year, the government ended these payments, but it was still a major gripe among peasants that large landholders held big amounts of the best land, while peasants were largely forced to remain in their villages (mir) which determined how land would be redistributed among its members, and that was responsible for collecting and transmitting taxes.

Basically, the breakdown of public order in 1917 led to an agrarian revolution, as peasants seized land still held by landowners and redistributed it among themselves (again, still in the village system). This actually happened with the February revolution, not the Bolshevik October revolution - a major breakdown in discipline and coherence among Russian troops at the front in World War I occurred as soldiers basically left and walked home in order to make sure they got a piece of the action in their village. The Provisional Government, being "provisional", didn't really have a clear policy on the matter, while the Bolsheviks wholeheartedly supported the redistribution (hence their slogan at the time, "Peace, Land, Bread"). However, the Bolsheviks, neither at this time nor after their takeover, actually led this redistribution: it was largely done at the local level, and then the Bolshevik authorities essentially ratified the new status quo. The Fundamental Law of Land Socialization in February 1918 was actually a bit of an ideological fudge, since it technically abolished all private ownership of land, but said that such land was open to use by the "toiling masses" - the peasants and their villages would have just said it belonged to them now.

Anyway, so far, so good. So things were better for the peasants, right? Well...a little hiccup came along the way, and that was the 1918-1921 Russian Civil War. This was, to be blunt, pretty disastrous for the whole country, but in very specific ways for the peasantry. The country essentially deindustrialized and deurbanized during the war - lots of people in big cities like Petrograd and Moscow still had personal links to villages, and with the breakdown in order and supply, a large number of them went back to their ancestral villages, where at least they could make a go at growing some food.

Unfortunately, the various armies battling over the former empire had their own designs on peasants' food supplies. The White armies confiscated food, and often tried to reimpose former landlords in areas they controlled, which was incredibly unpopular. If your community also happened to be Jewish, then there was a good chance they'd rape and murder many of you - pretty much anyone could expect to be robbed.

The Red Army was marginally better from this perspective - they were committed at least to not restoring landlords, and did not conduct pogroms. But they also instituted so-called "War Communism", which largely meant that armed detachments of soldiers, or workers or Red Guards from cities, would forcibly requisition food supplies for use by those still in the cities, or for the Red Army. This was also massively unpopular.

The combined result of this devastation was the 1921-1922 famine, located mostly in the Volga River valley. This caused at least something like a million deaths, aided by the spread of diseases like typhus. The death toll actually could have been far higher, but the Soviet authorities requested and received international aid, delivered by the American Relief Administration under Herbert Hoover (which was also feeding much of Europe after the end of the First World War).

After these catastrophes, Lenin backed off on agricultural policy, under the New Economic Policy. This essentially recognized some degree of private protection and sales by peasants, in an effort to get them to produce more. I get more into NEP and collectivization in this answer I wrote, but I'll copy the relevant parts before collectivization.

With the return of peace, the Soviets under Lenin undertook a "tactical retreat" with the NEP. Peasants' private ownership of land was recognized, and slowly rather than having produce requisitioned, peasants were taxed (at first in-kind, then paying money), and were allowed to sell their produce on the market, either to private traders (these would be the "NEPmen"), or to State procurement agencies directly, with the State offering fixed prices. The goal was that this mechanism would encourage peasants to produce again, and provide foodstuffs to the cities in return for manufactured goods.

However, there were a number of issues with this approach. One was the so-called "Scissors Crisis" which was discussed by Soviet planners in 1923: with peasants producing more foodstuffs, the supply for agricultural goods dropped. However, manufactured goods' prices continued to rise - industry was heavily damaged and a lot of capital went into reconstruction in the 1920s, with distribution of manufactured goods still being something of a mess. Therefore, peasants' purchasing power was effectively being eroded, and there was less incentive for peasants to produce for urban markets (why not just go with subsistence agriculture and not bother with the whole mess?). This in turn led to the "Grain Crisis" of 1928. State grain procurement had gone from 8.4 million tons in 1925-26, to 10.6 million tons in 1926-27, and then had slumped to 5.4 million tons in 1927-1928. The Soviet government in particular feared for its ability to feed Leningrad, Moscow, the Red Army, and vital agricultural regions not producing foodstuffs, such as the cotton-growing areas of Central Asia. What happened?

Overall, peasants were not selling as much produce, and there were a number of reasons why. First was the issue of the price scissors: why sell increasingly cheap foodstuffs for increasingly dear manufactured goods? The peasants themselves were also eating better, and thus selling less of their food as "surplus". Finally, there were rumors of a new international war in 1927 among the peasantry, and this combined with fears of renewed famine meant that peasants held on to food in anticipation of hungry days ahead.

This procurement crisis came at a time when members of the Soviet government and Bolshevik party were vigorously debating the economic future of the USSR. Trotsky, before his alienation and fall, had wanted a push towards industrialization, which would involve obtaining or squeezing capital out of the peasantry to finance it, while the "Right", embodied by Nikolai Bukharin, had wanted to appease the peasantry more (this was derided as "riding to socialism on a peasant nag"). Stalin had initially sided with Bukharin, but now began to switch his thinking; however most of the party rank and file considered NEP a temporary and tactical measure at best. Paying the peasantry more for their produce would both threaten the capital accumulation the government needed if it wanted to invest more in industrial projects, and would also (in party members' minds) indicate yet more surrendering to the peasantry. It's worth remembering that at this period, there was extremely little party structure in Soviet villages, and the peasantry was not seen as a natural source of support for Bolshevism. At this point, in early 1928, Stalin turned towards sterner measures.

So, in summary - peasant communities gained a long-cherished goal of confiscation of land previously held by landlords, and the Soviet regime basically supported and recognized this. However, the 1917-1928 period saw warfare, famine, and peasant uprisings (there was a major uprising against the Soviet authorities in Tambov in the 1920s). NEP saw a marked improvement in the economic situation for peasant communities, but there were still major issues, like a lack of finished goods to buy from cities, and a fear among peasants that sooner or later the authorities would stop being lenient with them. Which mostly proved to be correct.